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Showing votes from 2024-01-19 12:30 to 2024-01-23 11:30 | Next meeting is Friday Oct 25th, 11:30 am.
We demonstrate the explicit realisation of the ultra-slow roll phase in the framework of the effective field theory of single-field Galileon inflation. The pulsar timing array (PTA) collaboration hints at the scalar-induced gravity waves (SIGW) from the early universe as an explanation for the origin of the observed signal, which, however, leads to an enhancement in the amplitude of the scalar power spectrum giving rise to the overproduction of primordial black holes (PBHs). In the setup under consideration, we examine the generation of SIGW consistent with PTA (NANOGrav15 and EPTA) data and address the PBH overproduction issue assuming linear approximations for the over-density without incorporating non-Gaussian effects from the comoving curvature perturbation. The framework is shown to give rise to SIGWs well consistent with the PTA signal with comfortable PBH abundance, $10^{-3} \lesssim f_{\rm PBH} < 1$, of near solar-mass black holes.
We propose a specialized parameterization for the Hubble parameter, inspired by $\Lambda$CDM cosmology, to investigate the cosmic expansion history of the Universe. This parameterization is employed to analyze the Universe's late-time behavior within the context of $Q^n$ gravity, where $Q$ represents non-metricity. By using data from 57 Hubble data points, 1048 supernova (SNe) data points, and 6 baryon acoustic oscillation (BAO) data points, we determine the optimal values for the model parameters. Additionally, we explore three distinct cosmological models based on the parameter $n$, specifically when it takes on the values of $0.55$, $1.5$, and $2.0$. The results of our analysis indicate that our proposed parameterization, along with the associated models for different values of $n$, predicts an accelerated cosmic expansion phase.
In this paper we study the impact of a recent quasar datasample in the constraint of the free parameters of an extension of general relativity. As a ruler to test, we use Rastall gravity in the context of background cosmology being a simple extension to general relativity. We compare the results from quasars dataset with other known samples such as cosmic chronometers, supernovae of the Ia type, baryon acoustic oscillations, HII galaxies, and also a joint analysis. Results are consistent with the standard cosmological model emphasizing that Rastall gravity is equivalent to General Relativity. According to the constraints provided from the joint sample, the age of the Universe is $\tau_U = 12.601^{+0.067}_{-0.066}$ Gyrs and the transition to an accelerated phase occurs at $z_T=0.620\pm0.025$ in the redshift scale, being only the phase transition consistent with the standard paradigm and having a younger Universe. With the quasars sample, the universe age differs with that expected in $\Lambda$CDM having a result of $\tau_U = 11.958^{+0.139}_{-0.109}$ Gyrs with a transition at $z_T=0.652\pm0.032$ this last consistent with standard cosmology. A remarkable result is that quasars constraints has the capability to differentiate among general relativity and Rastall gravity due to the result for the parameter $\lambda=-2.231^{+0.785}_{-0.546}$. Moreover, the parameter $j$ under quasars constraints suggests that the cause of the late universe's acceleration is a dark energy fluid different from a cosmological constant.
Effective field theories (EFTs) of heavy particles coupled to the inflaton are rife with operator redundancies, frequently obscured by sensitivity to both boundary terms and field redefinitions. We initiate a systematic study of these redundancies by establishing a minimal operator basis for an archetypal example, the abelian gauge-Higgs-inflaton EFT. Working up to dimension 9, we show that certain low-dimensional operators are entirely redundant and identify new non-redundant operators with potentially interesting cosmological collider signals. Our methods generalize straightforwardly to other EFTs of heavy particles coupled to the inflaton.
21-cm cosmology provides an exciting opportunity to probe new physics dynamics in the early universe. In particular, a tiny sub-component of dark matter that interacts strongly with the visible sector may cool the gas in the intergalactic medium and significantly alter the expected absorption signal at Cosmic Dawn. However, the information about new physics in this observable is obscured by astrophysical systematic uncertainties. In the absence of a microscopic framework describing the astrophysical sources, these uncertainties can be encoded in a bottom up effective theory for the 21-cm observables in terms of unconstrained astrophysical fluxes. In this paper, we take a first step towards a careful assessment of the degeneracies between new physics effects and the uncertainties in these fluxes. We show that the latter can be constrained by combining measurements of the UV luminosity function, the Planck measurement of the CMB optical depth to reionization, and an upper bound on the unresolved X-ray flux. Leveraging those constraints, we demonstrate how new physics signatures can be disentangled from astrophysical effects. Focusing on the case of millicharged dark matter, we find sharp predictions, with small uncertainties within the viable parameter space.
We present new measurements of the values of the Hubble constant, matter density, dark energy density, and dark energy density equation-of-state parameters from a full strong lensing analysis of the observed positions of 89 multiple images and 4 measured time delays of SN Refsdal multiple images in the Hubble Frontier Fields galaxy cluster MACS J1149.5+2223. By strictly following the identical modelling methodology as in our previous work, that was done before the time delays were available, our cosmographic measurements here are essentially blind based on the frozen procedure. Without using any priors from other cosmological experiments, in an open $w$CDM cosmological model, through our reference cluster mass model, we measure the following values: $H_0 = 65.1^{+3.5}_{-3.4}$ km s$^{-1}$ Mpc$^{-1}$, $\Omega_{\rm DE}=0.76^{+0.15}_{-0.10}$, and $w=-0.92^{+0.15}_{-0.21}$ (at the 68.3% confidence level). No other single cosmological probe is able to measure simultaneously all these parameters. Remarkably, our estimated values of the cosmological parameters, particularly $H_0$, are very robust and do not depend significantly on the assumed cosmological model and the cluster mass modelling details. The latter introduce systematic uncertainties on the values of $H_0$ and $w$ which are found largely subdominant compared to the statistical errors. The results of this study show that time delays in lens galaxy clusters, combined with extensive photometric and spectroscopic information, offers a novel and competitive cosmological tool.
While the available set of Gamma-ray Burst (GRB) data with known redshift is currently limited, a much larger set of GRB data without redshift is available from different instruments. This data includes well-measured prompt gamma-ray flux and spectral information. We estimate the redshift of a selection of these GRBs detected by Fermi-GBM and Konus-Wind using Machine Learning techniques that are based on spectral parameters. We find that Deep Neural Networks with Random Forest models employing non-linear relations among input parameters can reasonably reproduce the pseudo-redshift distribution of GRBs, mimicking the distribution of GRBs with spectroscopic redshift. Furthermore, we find that the pseudo-redshift samples of GRBs satisfy (i) Amati relation between the peak photon energy of the time-averaged energy spectrum in the cosmological rest frame of the GRB ${E}_{\rm i, p}$ and the isotropic-equivalent radiated energy ${E}_{\rm iso}$ during the prompt phase; and (ii) Yonetoku relation between ${E}_{\rm i, p}$ and isotropic-equivalent luminosity ${L}_{\rm iso}$, both measured during the peak flux interval.
The squeezed limit of the primordial curvature bispectrum is an extremely sensitive probe of new physics and encodes information about additional fields active during inflation such as their masses and spins. In the conventional setup, additional fields are stable with a positive mass squared, and hence induce a decreasing signal in the squeezed limit, making a detection challenging. Here we consider a scalar field that is temporarily unstable by virtue of a transient tachyonic mass, and we construct models in which it is embedded consistently within inflation. Assuming IR-finite couplings between the tachyon and the inflaton, we find an exchange bispectrum with an enhanced long-short scale coupling that grows in the squeezed limit parametrically faster than local non-Gaussianity. Our approximately scale-invariant signal can be thought of as a cosmological tachyon collider. In a sizeable region of parameter space, the leading constraint on our signal comes from the cross correlation of $\mu$-type spectral distortions and temperature anisotropies of the microwave background, whereas temperature and polarization bispectra are less sensitive probes. By including anisotropic spectral distortions in the analysis, future experiments such as CMB-S4 will further reduce the allowed parameter space.
We use updated gas mass fraction measurements of 44 massive dynamically relaxed galaxy clusters collated in ~\cite{Mantz22} to distinguish between the standard $\Lambda$CDM model and $R_h=ct$ universe. For this purpose, we use Bayesian model selection to compare the efficacy of both these cosmological models given the data. The gas mass fraction is modeled using both cosmology-dependent terms and also astrophysical parameters, which account for the variation with cluster mass and redshift. We find a Bayes factor of 50 for $\Lambda$CDM as compared to $R_h=ct$. This implies that $\Lambda$CDM is very strongly favored compared to $R_h=ct$.
We introduce a novel framework for studying small-scale primordial perturbations and their cosmological implications. The framework uses a deep reinforcement learning to generate scalar power spectrum profiles that are consistent with current observational constraints. The framework is shown to predict the abundance of primordial black holes and the production of secondary induced gravitational waves. We demonstrate that the set up under consideration is capable of generating predictions that are beyond the traditional model-based approaches.
A viable radiation dominated era in the early universe is best described by the standard (FLRW) model of cosmology. In this short review, we demonstrate reconstruction of the forms of F(R) in the modified theory of gravity and the metric compatible F(T) together with the symmetric F(Q) in alternative teleparallel theories of gravity, from different perspectives, primarily rendering emphasis on a viable FLRW radiation era. Inflation has also been studied for a particular choice of the scalar potential. The inflationary parameters are found to agree appreciably with the recently released observational data.
In this work we study the GW170817-compatible Einstein-Gauss-Bonnet theories during the reheating and the end of inflationary era. Given the scalar field potential $V(\phi)$ which can have some intrinsic importance for the theory, determining the scalar coupling function $\xi(\phi)$ can be cumbersome due to lack of analyticity. The GW170817 observation constrains the scalar coupling function and the scalar field potential to have some interdependence, thus during the slow-roll era one can calculate the scalar coupling function. However, when the slow-roll era ends, it is expected that the scalar coupling function should have a different form and the same applies for the reheating era, assuming that the scalar potential of the theory does not change. In this work we exactly aim to highlight this feature of Einstein-Gauss-Bonnet theories, as the Universe evolves through distinct sequential evolution eras, and we focus on how to determine the scalar coupling function during the various evolutionary eras, from inflation to the reheating era. Regarding both the end of the inflationary era and the reheating era, it is found that the Hubble rate obeys a constant-roll-like condition of the form $\dot{H}=\delta H^2$, thus the determination of the scalar Gauss-Bonnet function $\xi(\phi)$ is reduced to solving a differential equation. A mentionable feature of the era exactly at the end of inflation is that the Klein-Gordon equation is decoupled from the field equations, because the Gauss-Bonnet invariant is zero. We provide several examples of interest to support our arguments.
The ages of globular clusters (GC) are conventionally constrained by models that adhere to the accepted age of the Universe, preventing their ages from exceeding approximately 13.8 Gyr. However, a recent study by llorente de Andr\'es (2023) challenges this paradigm. Drawing on the relationship between the number of blue straggler stars (BSs) and the relaxation time, the study proposes that the age of the cluster NGC104 falls between 19.04 and 20.30 Gyr. Extending this approach, the present work investigates GCs NGC 5634 and NGC 5024, finding their ages to be between 15.8 and 21.6 Gyr, surpassing the accepted age of the Universe. A plausible explanation aligns with Gupta's model (Gupta 2023), suggesting a Universe age of around 26.7 billion years, consistent with early universe observations from the James Webb Space Telescope (JWST). Additionally, four other GCs (IC 4499, NGC 6273, NGC 5824 and NGC 4833) support Gupta's model. The implications of these extended GC ages challenge our current cosmic timeline understanding, prompting a comprehensive reassessment of cosmological paradigms in light of these intriguing observational results.
A viable model of large-field (chaotic) inflation with efficient production of primordial black holes is proposed in Starobinsky-like (modified) supergravity leading to the "no-scale-type" K\"ahler potential and the Wess-Zumino-type ("renormalizable") superpotential. The cosmological tilts are in good (within $1\sigma$) agreement with Planck measurements of the cosmic microwave background radiation. In addition, the power spectrum of scalar perturbations has a large peak at smaller scales, which leads to a production of primordial black holes from gravitational collapse of large perturbations with the masses about $10^{17}$ g. The masses are beyond the Hawking (black hole) evaporation limit of $10^{15}$ g, so that those primordial black holes may be viewed as viable candidates for part or the whole of the current dark matter. The parameters of the superpotential were fine-tuned for those purposes, while the cubic term in the superpotential is essential whereas the quadratic term should vanish. The vacuum after inflation (relevant to reheating) is Minkowskian. The energy density fraction of the gravitational waves induced by the production of primordial black holes and their frequency were also calculated in the second order with respect to perturbations.
A numerical detection of the $\tau$-driven transition of galaxy spins is presented, where $\tau$ is the degree of misalignment between the initial tidal field and protogalaxy inertia tensors. Analyzing the data from the IllustrisTNG 300-1 simulations, we first measure the values of $\tau$ at the protogalactic sites found by tracing the constituents of the galactic halos in the mass range of $10.5\le \log \left[M_{h}/(h^{-1}M_{\odot})\right] \le 13$ back to the initial stage, $z_{i}=127$. The probability density functions of $\tau$ are shown to be well modeled by the $\Gamma$-distributions, whose shape and scale parameters turn out to have universal values on a certain critical scale. Then, we investigate how the strength and tendency of the galaxy spin alignments with the principal axes of the local tidal fields depend on the initial condition, $\tau$. It is found that on the scale lower than the critical one, the galaxy spin transition occurs at two different thresholds from the major to intermediate and from the intermediate to minor principal axes of the local tidal fields, respectively. Noting that the $\tau$-dependent spin transition supersedes in strength the previously found mass-dependent, morphology-dependent, and radius-dependent counterparts, we suggest that $\tau$ should be the key driver of all types of the galaxy spin transition and that the present galaxy spins are indeed excellent fossil records of the initial condition.
The Bayes factor surface is a new way to present results from experimental searches for new physics. Searches are regularly expressed in terms of phenomenological parameters - such as the mass and cross-section of a weakly interacting massive particle. Bayes factor surfaces indicate the strength of evidence for or against models relative to the background only model in terms of the phenomenological parameters that they predict. They provide a clear and direct measure of evidence, may be easily reinterpreted, but do not depend on choices of prior or parameterization. We demonstrate the Bayes factor surface with examples from dark matter, cosmology, and collider physics.
This paper analyzes the possibility of bouncing and non-bouncing universes in the framework of four-dimensional Einstein-Gauss-Bonnet (4D-EGB) gravity, corresponding respectively to negative and positive coupling constants $\lambda$ of the Gauss-Bonnet term. We also use the Horndeski-type scalar-tensor theory to assess the role of a scalar charge $C$ as a geometrical contribution to the radiation in the Universe. We modify the expansion history of the universe to allow for modifications induced by the 4D-EGB gravity. Using Planck measurements of the cosmic microwave background anisotropies as well as various datasets of baryonic acoustic oscillations, we set the upper bounds $\lambda \le 10^{-16} \text{(km/s/Mpc)}^{-2} $ and $\lambda \le 10^{-30} \text{(km/s/Mpc)}^{-2} $ for the non-bouncing and bouncing scenarios. The upper limit in the latter case is mainly driven by the requirement to conservatively respect the thermal history at energy scales of the standard model of particle physics. We also find that the contribution of the geometrical radiation-like term of the model cannot exceed 10\% of the current radiation in the Universe. This study shows the feasibility of a bouncing universe, even with a normal matter sector, in the 4D-EGB gravity. More theoretical investigation is required to further explore possible observational predictions of the model that can distinguish between general relativity and 4D-EGB gravity.
In this study, we conducted a detailed analysis of the core parameter of Warm Higgs Inflation (WHI) $-$ the dissipation coefficient ($Q$). As a crucial parameter in the warm inflation process, $Q$ exerts profound influences on the entire evolutionary process. By meticulously deriving the relationships between various quantities and $Q$, we successfully circumvented the common preconceptions regarding strong and weak dissipation, laying the foundation for a more accurate exploration of their interconnections. Taking into account the constraints imposed by Cosmic Microwave Background, we observed that the dissipation coefficient $Q$ remains at extremely low levels throughout the entire warm inflation process, i.e., $Q \ll 1$. This observation indicates that WHI falls under the category of weakly dissipative warm inflation. Despite being weakly dissipative, $Q$ still plays a crucial role in the evolution of temperature, energy, and other quantities, highlighting its significance and non-negligibility. We delved deeper into the impact of the primordial power spectrum on the dissipation coefficient $Q$ during the warm inflation process, discovering that the dependency is not significant. Consequently, this naturally leads to the unobtrusive dependence of the gravitational wave power spectrum on $Q$. Finally, we found that gravitational waves generated by WHI hold the potential for verification in future observational experiments, especially through the SKA100 experiment. These findings provide a theoretical support for a more profound understanding of the early evolution of the universe.
We report the identification of 64 new candidates of compact galaxies, potentially hosting faint quasars with bolometric luminosities of $L_\mathrm{bol} = 10^{43}$--10$^{46}$ erg s$^{-1}$, residing in the reionization epoch within the redshift range of $6 \lesssim z \lesssim 8$. These candidates were selected by harnessing the rich multiband datasets provided by the emerging JWST-driven extragalactic surveys, focusing on COSMOS-Web, as well as JADES, UNCOVER, CEERS, and PRIMER. Our search strategy includes two stages: applying stringent photometric cuts to catalog-level data and detailed spectral energy distribution fitting. These techniques effectively isolate the quasar candidates while mitigating contamination from low-redshift interlopers, such as brown dwarfs and nearby galaxies. The selected candidates indicate physical traits compatible with low-luminosity active galactic nuclei, likely hosting $\approx10^5$--$10^7~M_\odot$ supermassive black holes (SMBHs) living in galaxies with stellar masses of $\approx10^8$--$10^{10}~M_\odot$. The SMBHs selected in this study, on average, exhibit elevated mass compared to their hosts, with the mass ratio distribution slightly higher than those of galaxies in the local universe. As with other high-$z$ studies, this is at least in part due to the selection method for these quasars. An extensive Monte Carlo analysis provides compelling evidence that heavy black hole seeds from the direct collapse scenario appear to be the preferred pathway to mature this specific subset of SMBHs by $z\approx7$. This work underscores the significance of further spectroscopic observations, as the quasar candidates presented here offer exceptional opportunities to delve into the nature of the earliest galaxies and SMBHs formed during cosmic infancy.
The 21-cm spectral line widths, $w_{50}$, of galaxies are an approximate tracer of their dynamical masses, such that the dark matter halo mass function is imprinted in the number density of galaxies as a function of $w_{50}$. Correcting observed number counts for survey incompleteness at the level of accuracy needed to place competitive constraints on warm dark matter (WDM) cosmological models is very challenging, but forward-modelling the results of cosmological hydrodynamical galaxy formation simulations into observational data space is more straightforward. We take this approach to make predictions for an ALFALFA-like survey from simulations using the EAGLE galaxy formation model in both cold (CDM) and WDM cosmogonies. We find that for WDM cosmogonies more galaxies are detected at the low-$w_{50}$ end of the 21-cm velocity width function than in the CDM cosmogony, contrary to what might na\"ively be expected from the suppression of power on small scales in such models. This is because low-mass galaxies form later and retain more gas in WDM cosmogonies (with EAGLE). While some shortcomings in the treatment of cold gas in the EAGLE model preclude placing definitive constraints on WDM scenarios, our analysis illustrates that near-future simulations with more accurate modelling of cold gas will likely make strong constraints possible, especially in conjunction with new 21-cm surveys such as WALLABY.
Axions and axion-like particles (ALPs) are leading candidates for dark matter. They are well motivated in many extensions of the Standard Model and supported by astronomical observations. We propose an iterative transformation of the existing facilities of the gravitational-wave detector and technology testbed GEO600, located near Ruthe in Germany, into a kilometre-scale upgrade of the laser-interferometric axion detector LIDA. The final DarkGEO detector could search for coincident signatures of axions and ALPs and significantly surpass the current constraints of both direct searches and astrophysical observations in the measurement band from $10^{-16}$ to $10^{-8}$ $\text{eV}$. We discuss realistic parameters and design sensitivities for the configurations of the different iteration steps as well as technical challenges known from the first LIDA results. The proposed DarkGEO detector will be well suited to probe the parameter space associated with predictions from theoretical models, like grand-unified theories, as well as from astrophysical evidence, like the cosmic infrared background.
Cosmic birefringence is the in-vacuo, frequency independent rotation of the polarization plane of linearly polarized radiation, induced by a parity-violating term in the electromagnetic Lagrangian. We implement an harmonic estimator for the birefringence field that only relies on the CMB E to B mode cross-correlation, thus suppressing the effect of cosmic variance from the temperature field. We derive constraints from Planck public releases 3 and 4, revealing a cosmic birefringence power spectrum consistent with zero at about $2\sigma$ up to multipole $L=1500$. Moreover, we find that the cross-correlations of cosmic birefringence with the CMB T-, E- and B-fields are also well compatible with null. The latter two cross-correlations are provided here for the first time up to $L=1500$.
We review the status of neutrino mass constraints obtained from cosmological observations, with a particular focus on the results derived considering Cosmic Microwave Background (CMB) data by various experiments (Planck, ACT and SPT), Baryon Acoustic Oscillation (BAO) determinations and other late-universe probes. We discuss the role played by priors and parameterizations in the Bayesian analyses, both at the time of determining neutrino masses or their ordering, and compare cosmological bounds with terrestrial constraints on both quantities.
We investigate the non-adiabatic effect of time-dependent deformations in the Milky Way (MW) halo potential on stellar streams. Specifically, we consider the MW's response to the infall of the Large Magellanic Cloud (LMC) and how this impacts our ability to recover the spherically averaged MW mass profile from observation using stream actions. Previously, action clustering methods have only been applied to static or adiabatic MW systems to constrain the properties of the host system. We use a time-evolving MW--LMC simulation described by basis function expansions. We find that for streams with realistic observational uncertainties on shorter orbital periods and without close encounters with the LMC, e.g. GD-1, the radial action distribution is sufficiently clustered to locally recover the MW mass profile across the stream radial range within a 2 sigma confidence interval determined using a Fisher information approach. For streams with longer orbital periods and close encounters with the LMC, e.g. Orphan-Chenab (OC), the radial action distribution disperses as the MW halo has deformed non-adiabatically. Hence, for OC streams generated in potentials that include a MW halo with any deformations, action clustering methods will fail to recover the mass profile within a 2 sigma uncertainty. Finally, we investigate whether the clustering of stream energies can provide similar constraints. Surprisingly, we find for OC-like streams, the recovered spherically averaged mass profiles demonstrate less sensitivity to the time-dependent deformations in the potential.
Although the $\Lambda$ Cold Dark Matter model is the most accredited cosmological model, information at high redshifts ($z$) between type Ia supernovae ($z=2.26$) and the Cosmic Microwave Background ($z=1100$) is crucial to validate this model further. To this end, we have discovered a sample of 1132 quasars up to $z=7.54$ exhibiting a reduced intrinsic dispersion of the relation between ultraviolet and X-ray fluxes, $\delta_\mathrm{F}=0.22$ vs. $\delta_\mathrm{F}=0.29$ ($24\%$ less), than the original sample. This gold sample, once we correct the luminosities for selection biases and redshift evolution, enables us to determine the matter density parameter $\Omega_M$ with a precision of 0.09. Unprecedentedly, this quasar sample is the only one that, as a standalone cosmological probe, yields such tight constraints on $\Omega_M$ while being drawn from the same parent population of the initial sample.
Cosmological analyses using galaxy clusters in optical/NIR photometric surveys require robust characterization of their galaxy content. Precisely determining which galaxies belong to a cluster is crucial. In this paper, we present the COlor Probabilistic Assignment of Clusters And BAyesiaN Analysis (Copacabana) algorithm. Copacabana computes membership probabilities for {\it all} galaxies within an aperture centred on the cluster using photometric redshifts, colours, and projected radial probability density functions. We use simulations to validate Copacabana and we show that it achieves up to 89\% membership accuracy with a mild dependency on photometric redshift uncertainties and choice of aperture size. We find that the precision of the photometric redshifts has the largest impact on the determination of the membership probabilities followed by the choice of the cluster aperture size. We also quantify how much these uncertainties in the membership probabilities affect the stellar mass--cluster mass scaling relation, a relation that directly impacts cosmology. Using the sum of the stellar masses weighted by membership probabilities ($\mu_{\star}$) as the observable, we find that Copacabana can reach an accuracy of 0.06 dex in the measurement of the scaling relation. These results indicate the potential of Copacabana and $\mu_{\star}$ to be used in cosmological analyses of optically selected clusters in the future.
The reappearance of supernova Refsdal provides the time-delay distance, which serves as a powerful tool to determine the Hubble constant ($H_0$). We give a cosmological-model-independent method to estimate $H_0$ through Gaussian process regression, using time-delay measurement from this lensed supernova in combination with supernova data from Pantheon+ sample. Using eight cluster lens models for supernova Refsdal, we infer $H_0 = 64.2^{+4.4}_{-4.3} \, \rm{km\,s^{-1}\,Mpc^{-1}}$ and using two cluster models most consistent with the observations, we infer $H_0 = 66.3^{+3.8}_{-3.6} \, \rm{km\,s^{-1}\,Mpc^{-1}}$. Our estimations of $H_0$ are in $1\sigma$ agreement with the results assuming a flat $\Lambda$CDM model and the uncertainties are comparable. Our constraint results on $H_0$ from the eight lens models and the two lens models indicate $2\sigma$ and $1.8\sigma$ tension with that estimated by SH0ES, respectively. However, our most probable values of $H_0$ from the two sets of lens models show good consistency with $H_0$ inferred from Planck CMB observations assuming $\Lambda$CDM model within $1\sigma$. We also find that our results for $H_0$ indicate $2\sigma$ deviations and $1.7\sigma$ deviations from the constraint results of $H_0$ using six time-delay quasars by H0LiCOW with the same analysis method.
We trace the connectivity of the cosmic web as defined by haloes in the Planck-Millennium simulation using a persistence and Betti curve analysis. We normalise clustering up to the second-order correlation function, and use our systematic topological analysis to correlate local information and properties of haloes with their multi-scale geometrical environment of the cosmic web (elongated filamentary bridges and sheetlike walls). We capture the multi-scale topology traced by the halo distribution through filtrations of the corresponding Delaunay tessellation. The resulting nested $\textit{alpha shapes}$ are sensitive to the local density, perfectly outline the local geometry, and contain the complete information on the multi-scale topology. We find a remarkable linear relationship between halo masses and topology: haloes of different mass trace environments with different topological signature. This is $\textit{topological bias}$, an environmental structure bias independent of the halo clustering bias associated with the two-point correlation function. This mass-dependent linear scaling relation allows us to take clustering into account and determine the overall connectivity from a limited sample of galaxies. The presence of topological bias has major implications for the study of voids and filaments in the observed distribution of galaxies. The (infra)structure and shape of these key cosmic web components will strongly depend on the underlying galaxy sample. Their use as cosmological probes, with their properties influenced by cosmological parameters, will have to account for the subtleties of topological bias. This is of particular relevance with the large upcoming galaxy surveys such as DESI, Euclid, and the Vera Rubin telescope surveys.
We have proposed that galaxy formation is catalyzed by the collision of infalling and outstreaming particles from leaky, horizonless astrophysical black holes, most likely gravastars, and based on this gave a model for the disk galaxy scale length. In this paper we modify our original scale length formula by including an activation probability $P$ for a collision to lead to nucleation of star formation. The revised scale length formula accords with both late time data and early universe data from the JWST, and suggests that galaxy dimensions should systematically get smaller as the observed redshift z increases. We also initiate a discussion of how particles recycling through gravastars can lead to a reduction in the temperature of the surrounding gas, triggering galaxy formation through enhanced star formation.
In this study, cosmological models are considered, where dark matter and dark energy are coupled and may exchange energy through non-gravitational interactions with one other. These interacting dark energy (IDE) models have previously been introduced to address problems with the standard $\Lambda$CDM model of cosmology (which include the coincidence problem, Hubble tension and $S_8$ discrepancy). However, conditions ensuring positive energy densities have often been overlooked. Assuming two different linear dark energy couplings, $Q = \delta H \rho_{\rm{de}}$ and $Q = \delta H \rho_{\rm{dm}}$, we find that negative energy densities are inevitable if energy flows from dark matter to dark energy (iDMDE regime) and that consequently, we should only seriously consider models where energy flows from dark energy to dark matter (iDEDM regime). To additionally ensure that these models are free from early time instabilities, we need to require that dark energy is in the `phantom' ($\omega<-1$) regime. This has the consequence that model $Q=\delta H \rho_{\rm{dm}}$ will end with a future big rip singularity, while $Q = \delta H \rho_{\rm{de}}$ may avoid this fate with the right choice of cosmological parameters.
We analytically solve the problem of Bose star growth in the bath of gravitationally interacting particles. We find that after nucleation of this object the bath is described by a self-similar solution of kinetic equation. Together with the conservation laws, this fixes mass evolution of the Bose star. Our theory explains, in particular, the slowdown of the star growth at a certain "core-halo" mass, but also predicts formation of heavier and lighter objects in magistral dark matter models. The developed "adiabatic" approach to self-similarity may be of interest for kinetic theory in general.
Gravitational waves (GWs) were recently detected for the first time. This revolutionary discovery opens a new way of learning about particle physics through GWs from first-order phase transitions (FOPTs) in the early Universe. FOPTs could occur when new fundamental symmetries are spontaneously broken down to the Standard Model and are a vital ingredient in solutions of the matter anti-matter asymmetry problem. The purpose of our work is to review the path from a particle physics model to GWs, which contains many specialized parts, so here we provide a timely review of all the required steps, including: (i) building a finite-temperature effective potential in a particle physics model and checking for FOPTs; (ii) computing transition rates; (iii) analyzing the dynamics of bubbles of true vacuum expanding in a thermal plasma; (iv) characterizing a transition using thermal parameters; and, finally, (v) making predictions for GW spectra using the latest simulations and theoretical results and considering the detectability of predicted spectra at future GW detectors. For each step we emphasize the subtleties, advantages and drawbacks of different methods, discuss open questions and review the state-of-art approaches available in the literature. This provides everything a particle physicist needs to begin exploring GW phenomenology.
We investigate how our baryon-loss limits from anomalous binary-pulsar period lengthening can be interpreted microscopically to yield specific constraints on the particle physics of baryon number violation within a neutron star. We focus on the possibility of anomalous baryon disappearance via dark baryon processes and on scenarios in which the produced dark-sector particles do not survive to influence the response of the star to baryon-number-violating effects. We flesh out the conditions for which this may occur, as well as other key assumptions. We then turn to the analysis of particle processes in the dense nuclear medium found at the core of a neutron star, employing the techniques of relativistic mean-field theory. Using our study of in-medium effects and limits on macroscopic baryon number violation we extract limits on in-vacuum baryon-number-violating processes, and we determine them for various equations of state. We conclude by noting the implications of our results for models of dark-sector-enabled baryogenesis.
Many symmetry breaking patterns in grand unified theories (GUTs) give rise to cosmic strings that eventually decay when pairs of GUT monopoles spontaneously nucleate along the string cores. These strings are known as metastable cosmic strings and have intriguing implications for particle physics and cosmology. In this article, we discuss the current status of metastable cosmic strings, with a focus on possible GUT embeddings and connections to inflation, neutrinos, and gravitational waves (GWs). The GW signal emitted by a network of metastable cosmic strings in the early universe differs, in particular, from the signal emitted by topologically stable strings by a suppression at low frequencies. Therefore, if the underlying symmetry breaking scale is close to the GUT scale, the resulting GW spectrum can be accessible at current ground-based interferometers as well as at future space-based interferometers, such as LISA, and at the same time account for the signal in the most recent pulsar timing data sets. Metastable cosmic strings thus nourish the hope that future GW observations might shed light on fundamental physics close to the GUT scale.
We study the perturbations up to the 2nd-order for a power-law inflation driven by a scalar field in synchronous coordinates. We present the 1st-order solutions, and analytically solve the 2nd-order perturbed Einstein equation and scalar field equation, give the 2nd-order solutions for all the scalar, vector, and tensor metric perturbations, as well as the perturbed scalar field. During inflation, the 1st-order tensor perturbation is a wave and is decoupled from other perturbations, the scalar metric perturbation and the perturbed scalar field are coupled waves, propagating at the speed of light, differing from those in the dust and relativistic fluid models. The 1st-order vector perturbation is not wave and just decreases during inflation. The 2nd-order perturbed Einstein equation is similar in structure to the 1st-order one, but various products of the 1st-order perturbations occur as the effective source, among which the scalar-scalar coupling is considered in this paper. The solutions of all the 2nd-order perturbations consist of a homogeneous part similar to the 1st-order solutions, and an inhomogeneous part in a form of integrations of the effective source. The 2nd-order vector perturbation is also a wave since the effective source is composed of the 1st-order waves. We perform the residual gauge transformations between synchronous coordinates up to the 2nd-order, and identify the 1st-order and 2nd-order gauge modes.
Gravitational-wave searches for cosmic strings are currently hindered by the presence of detector glitches, some classes of which strongly resemble cosmic string signals. This confusion greatly reduces the efficiency of searches. A deep-learning model is proposed for the task of distinguishing between gravitational wave signals from cosmic string cusps and simulated blip glitches in design sensitivity data from the future Einstein Telescope. The model is an ensemble consisting of three convolutional neural networks, achieving an accuracy of 79%, a true positive rate of 76%, and a false positive rate of 18%. This marks the first time convolutional neural networks have been trained on a realistic population of Einstein Telescope glitches. On a dataset consisting of signals and glitches, the model is shown to outperform matched filtering, specifically being better at rejecting glitches. The behaviour of the model is interpreted through the application of several methods, including a novel technique called waveform surgery, used to quantify the importance of waveform sections to a classification model. In addition, a method to visualise convolutional neural network activations for one-dimensional time series is proposed and used. These analyses help further the understanding of the morphological differences between cosmic string cusp signals and blip glitches. Because of its classification speed in the order of magnitude of milliseconds, the deep-learning model is suitable for future use as part of a real-time detection pipeline. The deep-learning model is transverse and can therefore potentially be applied to other transient searches.
During the last three years the pulsar timing arrays reported a series of repeated evidences of gravitational radiation (with stochastically distributed Fourier amplitudes) at a benchmark frequency of the order of $30$ nHz and characterized by spectral energy densities (in critical units) ranging between $10^{-8}$ and $10^{-9}$. While it is still unclear whether or not these effects are just a consequence of the pristine variation of the space-time curvature, the nature of the underlying physical processes would suggest that the spectral energy density of the relic gravitons in the nHz domain may only depend on the evolution of the comoving horizon at late, intermediate and early times. Along this systematic perspective we first consider the most conventional option, namely a post-inflationary modification of the expansion rate. Given the present constraints on the relic graviton backgrounds, we then show that such a late-time effect is unable to produce the desired hump in the nHz region. We then analyze a modified exit of the relevant wavelengths as it may happen when the gravitons inherit an effective refractive index from the interactions with the geometry. A relatively short inflationary phase leads, in this case, to an excess in the nHz region even if the observational data coming from competing experiments do not pin down exactly the same regions in the parameter space. We finally examine an early stage of increasing curvature and argue that it is not compatible with the observed spectral energy density unless the wavelengths crossing the comoving horizon at early times reenter in a decelerated stage not dominated by radiation.
Graviton-photon conversions in a given external electric or magnetic field, known as the Gertsenshtein mechanism, are usually treated using the four-potential for photons. In terms of the electric and magnetic (EM) fields, however, proper identification of the fields in curved spacetime is important. By misidentifying the fields in Minkowski form, as is often practiced in the literature, we show that the final equation for photon conversion is correct in transverse-tracefree gauge only for planar gravitational waves in a uniform and constant external field. Even in the former method, to recover the EM fields from the four-potential in curved spacetime, one should properly take into account the metric involved in the relation. By including the metric perturbation in the graviton conversion equation, we show that a magnetic environment can cause tachyonic instability term in gravitational wave equation.
Problems with the cosmological constant model of dark energy motivate the investigation of alternative scenarios. I make the first measurement of the dark energy equation of state using the hierarchical strong lensing time delay likelihood provided by TDCOSMO. I find that the combination of seven TDCOSMO lenses and 33 SLACS lenses is only able to provide a weak constraint on the dark energy equation of state, $w < -1.75$ at 68% confidence, which nevertheless implies the presence of a phantom dark energy component. When the strong lensing time delay data is combined with a collection of cosmic microwave background, baryon acoustic oscillation and Type Ia supernova data, I find that the equation of state is $w = -1.025\pm 0.029$.
Big Bang Nucleosynthesis (BBN) is a strong probe for constraining new physics including gravitation. $f(R)$ gravity theory is an interesting alternative to general relativity which introduces additional degrees of freedom known as scalarons. In this work we demonstrate the existence of black hole solutions in $f(R)$ gravity and develop a relation between scalaron mass and black hole mass. We have used observed bound on the freezeout temperature to constrain scalaron mass range by modifying the cosmic expansion rate at the BBN epoch. The mass range of primordial black holes (PBHs) which are astrophysical dark matter candidates is deduced. The range of scalaron mass which does not spoil the BBN era is found to be $10^{-16}-10^4 \text{ eV}$ for both relativistic and non-relativistic scalarons. The window $10^{-16}-10^{-14}$ eV of scalaron mass obtained from solar system constraint on PPN parameter is compatible with the BBN bound derived in this work. The PBH mass range is obtained as $10^6-10^{-14}\text{ }M_{\odot}$. Scalarons constrained by BBN are also eligible to accommodate axion like dark matter particles. The problem of ultra-light PBHs ($M \le 10^{-24} \text{ }M_\odot$) not constrained by the present study of BBN is still open. Estimation of deuterium (D) fraction and relative D+$^3$He abundance in the $f(R)$ gravity scenario shows that the BBN history mimics that of general relativity. While the PBH mass range is eligible for non-baryonic dark matter, the BBN bounded scalarons provide with an independent strong field test of $f(R)$ gravity. The PBH mass range obtained in the study is discussed in relation to future astronomical measurements.
In this study, we investigate how the baryonic effects vary with scale and local density environment mainly by utilizing a novel statistic, the environment-dependent wavelet power spectrum (env-WPS). With four state-of-the-art cosmological simulation suites, EAGLE, SIMBA, Illustris, and IllustrisTNG, we compare the env-WPS of the total matter density field between the hydrodynamic and dark matter-only (DMO) runs at $z=0$. We find that the clustering is most strongly suppressed in the emptiest environment of $\rho_\mathrm{m}/\bar\rho_\mathrm{m}<0.1$ with maximum amplitudes $\sim67-89$ per cent on scales $\sim1.86-10.96\ h\mathrm{Mpc}^{-1}$, and less suppressed in higher density environments on small scales (except Illustris). In the environments of $\rho_\mathrm{m}/\bar\rho_\mathrm{m}\geqslant0.316$ ($\geqslant10$ in EAGLE), the feedbacks also lead to enhancement features at intermediate and large scales, which is most pronounced in the densest environment of $\rho_\mathrm{m}/\bar\rho_\mathrm{m}\geqslant100$ and reaches a maximum $\sim 7-15$ per cent on scales $\sim0.87-2.62\ h\mathrm{Mpc}^{-1}$ (except Illustris). The baryon fraction of the local environment decreases with increasing density, denoting the feedback strength, and potentially explaining some differences between simulations. We also measure the volume and mass fractions of local environments, which are affected by $\gtrsim 1$ per cent due to baryon physics. In conclusion, our results show that the baryonic processes can strongly modify the overall cosmic structure on the scales of $k>0.1\ h\mathrm{Mpc}^{-1}$, which encourages further research in this direction.
Accurately measuring the Hubble parameter is vital for understanding the expansion history and properties of the universe. In this paper, we propose a new method that supplements the covariance between redshift pairs to improve the reconstruction of the Hubble parameter using the OHD dataset. Our approach utilizes a cosmological model-independent radial basis function neural network (RBFNN) to describe the Hubble parameter as a function of redshift effectively. Our experiments show that this method results in a reconstructed Hubble parameter of $H_0 = 67.1\pm9.7~\mathrm{km~s^{-1}~Mpc^{-1}}$ , which is more noise-resistant and fits better with the $\Lambda$CDM model at high redshifts. Providing the covariance between redshift pairs in subsequent observations will significantly improve the reliability and accuracy of Hubble parametric data reconstruction. Future applications of this method could help overcome the limitations of previous methods and lead to new advances in our understanding of the universe.
The search for sub-GeV dark matter via scattering on electrons has ramped up in the last few years. Like in the case of dark matter scattering on nuclei, electron-recoil-based searches also face an ultimate background in the form of neutrinos. The so-called ``neutrino fog'' refers to the range of open dark-matter parameter space where the background of neutrinos can potentially prevent a conclusive discovery claim of a dark matter signal from being made. In this study, we map the neutrino fog for a range of electron recoil experiments based on silicon, germanium, xenon and argon targets. In analogy to the nuclear recoil case, we also calculate the ''edge'' to the neutrino fog, which can be used as a visual guide to where neutrinos become an important background -- this boundary excludes some parts of the key theory milestones used to motivate these experiments.
There is probably not a black hole in the center of the sun. Despite this detail, our goal in this work to convince the reader that this question is interesting and that work studying stars with central black holes is well motivated. If primordial black holes exist then they may exist in sufficiently large numbers to explain the dark matter in the universe. While primordial black holes may form at almost any mass, the asteroid-mass window between $10^{-16} - 10^{-10} ~ \textrm{M}_\odot$ remains a viable dark matter candidate and these black holes could be captured by stars upon formation. Such a star, partially powered by accretion luminosity from a microscopic black hole in its core, has been called a `Hawking star.' Stellar evolution of Hawking stars is highly nontrivial and requires detailed stellar evolution models, which were developed in our recent work. We present here full evolutionary models of solar mass Hawking stars using two accretion schemes: one with a constant radiative efficiency, and one that is new in this work that uses an adaptive radiative efficiency to model the effects of photon trapping.
The evidence for a non-vanishing isotropic cosmic birefringence in recent analyses of the CMB data provides a tantalizing hint for new physics. Domain wall (DW) networks have recently been shown to generate an isotropic birefringence signal in the ballpark of the measured value when coupled to photons. In this work, we explore the axionic defects hypothesis in more detail and extending previous results to annihilating and late-forming networks, and by pointing out other smoking-gun signatures of the network in the CMB spectrum such as the anisotropic birefringent spectrum and B-modes. We also argue that the presence of cosmic strings in the network does not hinder a large isotropic birefringence signal because of an intrinsic environmental contribution coming from low redshifts thus leaving open the possibility that axionic defects can explain the signal. Regarding the remaining CMB signatures, with the help of dedicated 3D numerical simulations of DW networks, that we took as a proxy for the axionic defects, we show how the anisotropic birefringence spectrum combined with a tomographic approach can be used to infer the formation and annihilation time of the network. From the numerical simulations, we also computed the spectrum of gravitational waves (GWs) generated by the network in the post-recombination epoch and use previous searches for stochastic GW backgrounds in the CMB to derive for the first time a bound on the tension and abundance of networks with DWs that annihilate after recombination. Our bounds extend to the case where the network survives until the present time and improve over previous bounds by roughly one order of magnitude. Finally, we show the interesting prospects for detecting B-modes of DW origin with future CMB experiments.
Recently, Pandya et al. (2023) argued that the shapes of dwarf galaxies in JWST-CEERS observations show a prolate fraction that rises from ~25% at redshifts z=0.5-1 to ~50-80% at z=3-8. Here we suggest that this apparent change could result from a surface-brightness bias, favoring the detection of edge-on disks at low-luminosities and high-redshifts. Changing edge-on projections with an axis ratio of 10 to a face-on orientation reduces their apparent surface brightness by 2.5 magnitude per arcsec$^2$ and could shift a substantial fraction of the observed galaxies below the detection limit.
In this work, we have systematically investigated the Krylov complexity of curvature perturbation for the modified dispersion relation in inflation. Since many quantum gravitational frameworks could lead to this kind of modified dispersion relation, our analysis could be applied to the string cosmology, loop gravity, $\it e.t.c$. Following the Lanczos algorithm, we find the very early universe is an infinite, many-body, and maximal chaotic system. Our numerics shows that the Lanczos coefficient and Lyapunov index of the standard dispersion relation are mainly determined by the scale factor. As for the modified case, it is nearly determined by the momentum. In a method of the closed system, we discover that the Krylov complexity will show irregular oscillation before the horizon exits. The modified case will present faster growth after the horizon exists. As for the approach of an open system, we construct the exact wave function which is very robust only requiring the Lanczos coefficient proportional to $n$ (main quantum number). Based on it, we find the Krylov complexity and Krylov entropy could nicely recover in the case of a closed system under the weak dissipative approximation, in which our analysis shows that the evolution of Krylov complexity will not be the same with the original situation. We also find the inflationary period is a strong dissipative system. Meanwhile, our numerics clearly shows the Krylov complexity will grow during the whole inflationary period. But for the small scales, there will be a peak after the horizon exits. Our analysis reveals that the dramatic change in background (inflation) will significantly impact the evolution of Krylov complexity. Since the curvature perturbation will transit from the quantum level to the classical level. We could expect that the decoherence will highly impact the Krylov complexity during inflation.
In dense neutrino environments like core-collapse supernovae (CCSNe) and neutron star mergers (NSMs), neutrinos can undergo fast flavor conversions (FFC) when their angular distribution of neutrino electron lepton number ($\nu$ELN) crosses zero along some directions. While previous studies have demonstrated the detection of axisymmetric $\nu$ELN crossings in these extreme environments, non-axisymmetric crossings have remained elusive, mostly due to the absence of models for their angular distributions. In this study, we present a pioneering analysis of the detection of non-axisymmetric $\nu$ELN crossings using machine learning (ML) techniques. Our ML models are trained on data from two CCSN simulations, one with rotation and one without, where non-axisymmetric features in neutrino angular distributions play a crucial role. We demonstrate that our ML models achieve detection accuracies exceeding 90\%. This is an important improvement, especially considering that a significant portion of $\nu$ELN crossings in these models eluded detection by earlier methods.
The modification, by exotic sources of cooling, of the neutrino burst's duration following the core collapse of SN 1987A is known to provide a formidable constraint on axion interactions with matter. Compton-like nucleon-pion to nucleon-axion scattering has recently been shown to be an important mechanism, due to the large baryon and the non-negligible pion densities in the concerned proto-neutron star volume. In this context, the question arises of the role of hadronic matter beyond the first generation -- in particular strange matter. We perform a first quantitative study of this question, by consistently including the full baryon and meson octets in axion emission from Compton-like scattering and from baryon decay. We consider a range of possible thermodynamic conditions in the SN as well as various scenarios for the axion-quark couplings -- among them an "agnostic" scenario bounded only by data. Irrespective of the scenario considered, we find that axion emissivity introduces non-trivial correlations between flavour-diagonal axial couplings and constrains the off-diagonal counterpart to $O(10^{-1}$-$10^{-2})$ for $f_a = 10^9$ GeV.
The interaction of $\beta$-particles with the weakly ionized plasma background is an important mechanism for powering the kilonova transient signal from neutron star mergers. For this purpose, we present an implementation of the approximate fast-particle collision kernel, described by \cite{inokuti1971} following the seminal formulation of \cite{bethe1930}, in a spectral solver of the Vlasov-Maxwell-Boltzmann equations. In particular, we expand the fast-particle plane-wave atomic excitation kernel into coefficients of the Hermite basis, and derive the relevant discrete spectral system. In this fast-particle limit, the approach permits the direct use of atomic data, including optical oscillator strengths, normally applied to photon-matter interaction. The resulting spectral matrix is implemented in the MASS-APP spectral solver framework, in a way that avoids full matrix storage per spatial zone. We numerically verify aspects of the matrix construction, and present a proof-of-principle 3D simulation of a 2D axisymmetric kilonova ejecta snapshot. Our preliminary numerical results indicate that a reasonable choice of Hermite basis parameters for $\beta$-particles in the kilonova are a bulk velocity parameter $\vec{u}=0$, a thermal velocity parameter $\vec{\alpha}=0.5c$, and a 9x9x9 mode velocity basis set (Hermite orders 0 to 8 in each dimension). The results suggest that large-angle scatters of $\beta$-particles may be a non-negligible power source for kilonova luminosity and spectra.
We conducted an analysis of 45 bursts observed from 4U 1636$-$53. To investigate the mechanism behind the light curve profiles and the impact of thermonuclear X-ray bursts on the accretion environment in accreting neutron star low-mass X-ray binaries. This analysis employed both light curve and time-resolved spectroscopy methodologies, with data collected by the \textit{Insight}-HXMT instrument. We found that 30 bursts exhibited similar light curve profiles and were predominantly in the hard state, and two photospheric radius expansion (PRE) bursts were in the soft state. The light curves of most bursts did not follow a single exponential decay but displayed a dual-exponential behavior. The initial exponent had a duration of approximately 6 s. We utilized both the standard method and the `$f_{\rm a}$' method to fit the burst spectra. The majority of the `$f_{\rm a}$' values exceeded 1, indicating an enhancement of the persistent emission during the burst. Under the two comptonization components assumption, we suggest that the scattering of burst photons by the inner corona may mainly contribute to the persistent emission enhancement. We also observed an inverse correlation between the maximum $f_{\rm a}$ and the persistent emission flux in the non-PRE burst. This anti-correlation suggests that when the accretion rate is lower, there is a greater enhancement of persistent emission during the burst peak. The prediction based on Poynting-Robertson drag (P-R drag) aligns with this observed anti-correlation.
Quasi-periodic eruptions (QPEs) are intense repeating soft X-ray bursts with recurrence times about a few to ten hours from nearby galactic nuclei. The origin of QPEs is still unclear. In this work, we investigated the extreme mass ratio inspiral (EMRI) + accretion disk model, where the disk is formed from a previous tidal disruption event (TDE). In this EMRI+TDE disk model, the QPEs are the result of collisions between a TDE disk and a stellar mass object (a stellar mass black hole or a main sequence star) orbiting around a supermassive black hole (SMBH) in galactic nuclei. This model is flexible and comprehensive in recovering different aspects of QPE observations. If this interpretation is correct, QPEs will be invaluable in probing the orbits of stellar mass objects in the vicinity of SMBHs, and further inferring the formation of EMRIs which is one the primary targets of spaceborne gravitational wave missions. Taking GSN 069 as an example, we find the EMRI wherein is of low eccentricity ($e<0.1$ at 3-$\sigma$ confidence level) and semi-major axis about $O(10^2)$ gravitational radii of the central SMBH, which is consistent with the prediction of the wet EMRI formation channel, while incompatible with alternatives.
Neutron star (NS) binaries can be potentially intriguing gravitational wave (GW) sources, with both high- and low-frequency radiations from the possibly aspherical individual stars and the binary orbit, respectively. The successful detection of such a dual-line source could provide fresh insights into binary geometry and NS physics. In the absence of electromagnetic observations, we develop a strategy for inferring the spin-orbit misalignment angle using the tight dual-line double NS system under the spin-orbit coupling. Based on the four-year joint detection of a typical dual-line system with LISA and Cosmic Explorer, we find that the misalignment angle and the NS moment of inertia can be measured with sub-percentage and 5% accuracy, respectively.
Light curves of ellipsoidal variables collected by the Optical Gravitational Lensing Experiment (OGLE) were analyzed, in order to search for dormant black hole candidates. After the preselection based on the amplitude of ellipsoidal modulation, each object was investigated by means of the spectral energy distribution fit, which allowed us to select objects that are in close agreement with the spectrum of a single stellar object. After this final step of the preselection process, we were left with only fourteen objects that were then investigated in detail. For each candidate, we estimated basic physical parameters such as temperature, mass, luminosity, and, in some cases, radial velocity semi-amplitude. One of the objects turned out to be a spotted star while the rest are considered black-hole binary candidates. In the end, we present an alternative explanation for the ellipsoidal modulation in the form of contact binaries, which are not only vast in number, contrary to black-hole binaries, but are also in much better agreement with the radial velocity estimates for some of the systems analyzed. Even if the presented arguments suggest a noncompact character of the companion objects, each of them should be observed spectroscopically in order to verify the compact object hypothesis.
The detection of GW170817/GRB170817A implied the strong association between short gamma-ray bursts (SGRBs) and binary neutron star (BNS) mergers which produce gravitational waves (GWs). More evidence is needed to confirm the association and reveal the physical processes of BNS mergers. The upcoming High Altitude Detection of Astronomical Radiation (HADAR) experiment, excelling in a wide field of view (FOV) and a large effective area above tens of GeV, is a hope for the prompt detection of very-high-energy (VHE; > 10 GeV) SGRBs. The aim of this paper is to simulate and analyse GW/SGRB joint detections by future GW detector networks in synergy with HADAR, including the second generation LIGO, Virgo and KAGRA and the third generation ET and CE. We provide a brief introduction of the HADAR experiment for SGRB simulations and its expected SGRB detections. For GW simulations, we adopt a phenomenological model to describe GWs produced by BNS mergers and introduce the signal-noise ratios (SNRs) as detector responses. Following a theoretical analysis we compute the redshift-dependent efficiency functions of GW detector networks. We then construct the simulation of GW detection by Monte Carlo sampling. We compare the simulated results of LIGO-Virgo O2 and O3 runs with their actual detections as a check. The combination of GW and SGRB models is then discussed for joint detection, including parameter correlations, triggered SNRs and efficiency skymaps. The estimated joint detection rates are 0.09-2.52 per year for LHVK network with HADAR under different possible configurations, and approximately 0.27-7.89 per year for ET+CE network with HADAR.
We analyzed an observation with the Nuclear Spectroscopic Telescope Array of the black-hole X-ray binary MAXI J1535-571 in the soft intermediate state, in which we detected a 2.5-ks long flare. Our spectral fitting results suggest that MAXI J1535-571 possesses a high spin of 0.97 (-0.10/+0.02) and a low inclination of approximately 24 deg. We observed a gradual increase in the inner disc radius, as determined from fits to the continuum spectrum. This trend is inconsistent with an increased flux ratio of the thermal component, as well as the source evolving towards the soft state. This inconsistency may be attributed to a gradual decrease of the color correction factor. Additionally, with a flare velocity of approximately 0.5 c and a higher hardness ratio during the flare period, the quasi-simultaneous detection of a type-B QPO in the Neutron Star Interior Composition Explorer data, and quasi-simultaneous ejecta launch through radio observations collectively provide strong evidence supporting the possibility that the flare originated from a discrete jet ejection.
Long-lived radioactive by-products of nucleosynthesis provide an opportunity to trace the flow of ejecta away from its sources for times beyond where ejecta can be seen otherwise. Gamma rays from such radioactive decay in interstellar space can be measured with space-borne telescopes. A prominent useful example is 26Al with a radioactive decay time of one My. Such observations have revealed that typical surroundings of massive stars are composed of large cavities, extending to kpc sizes. Implications are that material recycling into new stars is twofold: rather direct as parental clouds are hosts to new star formation triggered by feedback, and more indirect as these large cavities merge with ambient interstellar gas after some delay. Kinematic measurements of hot interstellar gas carrying such ejecta promises important measurements complementing stellar and dense gas kinematics.
Gamma-ray bursts (GRBs) have been proposed as one of promising sources of ultra-high-energy cosmic rays (UHECRs), but observational evidence is still lacking. The nearby B.O.A.T. (brightest of all time) GRB 221009A, an once-in-1000-year event, is able to accelerate protons to $\sim 10^{3}$ EeV. Protons arriving at the Milky Way are dominated by neutron-decay-induced protons. The inter-galactic magnetic fields would not yield a sizable delay of the $\geq 10{\rm~EeV}$ cosmic rays if its strength is $\lesssim 10^{-13}{\rm~G}$, while Galactic magnetic fields would cause a significant time delay. We predict that, an UHECR burst from GRB 221009A would be detectable by the Pierre Auger Observatory and the TA$\times$4, within $\sim$ 10 years. The detection of such an UHECR outburst will provide the direct evidence for UHECR acceleration in GRBs.
We report observations of a powerful ionized gas outflow in a z = 4.1 luminous ($ L_{1.4GHz} \sim 10^{28.3} \ W \ Hz^{-1}$) radio galaxy TNJ1338-1942 hosting an obscured quasar using the Near Infrared Spectrograph (NIRSpec) on board JWST. We spatially resolve a large-scale (~15 kpc) outflow and measure resolved outflow rates. The outflowing gas shows velocities exceeding 900 $ km \ s^{-1}$ and broad line profiles with line widths exceeding 1200 $ km \ s^{-1}$ located at ~10 kpc projected distance from the central nucleus. The outflowing nebula spatially overlaps with the brightest radio lobe, indicating that the powerful radio jets are responsible for the extraordinary kinematics exhibited by the ionized gas. The ionized gas is possibly ionized by the central obscured quasar with a contribution from shocks. The spatially resolved mass outflow rate shows that the region with the broadest line profiles exhibits the strongest outflow rates, with an integrated mass outflow rate of ~500 $ M_{\odot} \ yr^{-1}$. Our hypothesis is that an over-pressured shocked jet fluid expands laterally to create an expanding ellipsoidal "cocoon" that causes the surrounding gas to accelerate outwards. The total kinetic energy injected by the radio jet is about 3 orders of magnitude larger than the total kinetic energy measured in the outflowing ionized gas. This implies that kinetic energy must be transferred inefficiently from the jets to the gas. The bulk of the deposited energy possibly lies in the form of hot (~$ 10^7$ K) X-ray-emitting gas.
Three-dimensional modeling has reached a level of maturity to provide detailed predictions of the gravitational wave emission in neutrino-driven core collapse supernovae. We review the status of these modeling efforts, current predictions for core collapse supernova gravitational wave emission, and the status of algorithms for the detection of core collapse supernova gravitational waves and the estimation of physical parameters associated with these events, which we hope to use to cull information about the central engine.
Strangeon stars, which are proposed to describe the nature of pulsar-like compact stars, have passed various observational tests. The maximum mass of a non-rotating strangeon star could be high, which implies that the remnants of binary strangeon star mergers could even be long-lived massive strangeon stars. We study rigidly rotating strangeon stars in the slowly rotating approximation, using the Lennard-Jones model for the equation of state. Rotation can significantly increase the maximum mass of strangeon stars with unchanged baryon numbers, enlarging the mass-range of long-lived strangeon stars. During spin-down after merger, the decrease of radius of the remnant will lead to the release of gravitational energy. Taking into account the efficiency of converting the gravitational energy luminosity to the observed X-ray luminosity, we find that the gravitational energy could provide an alternative energy source for the plateau emission of X-ray afterglow. The fitting results of X-ray plateau emission of some short gamma-ray bursts suggest that the magnetic dipole field strength of the remnants can be much smaller than that of expected when the plateau emission is powered only by spin-down luminosity of magnetars.
Understanding the high-energy emission processes and variability patterns are two of the most challenging research problems associated with relativistic jets. In particular, the long-term (months-to-years) flux variability at very high energies (VHE, $>$50 GeV) has remained an unexplored domain so far. This is possibly due to the decreased sensitivity of the Fermi Large Area Telescope (LAT) above a few GeV, hence low photon statistics, and observing constraints associated with the ground-based Cherenkov telescopes. This paper reports the results obtained from the 0.05$-$2 TeV Fermi-LAT data analysis of a sample of 29 blazars with the primary objective to explore their months-to-year long VHE flux variability behavior. This systematic search has led to, for the first time, the detection of significant flux variations in 5 blazars at $>$99\% confidence level, whereas, 8 of them exhibit variability albeit at a lower confidence level ($\sim$95\%-99\%). A comparison of the 0.05$-$2 TeV flux variations with that observed at 0.1$-$50 GeV band has revealed similar variability behavior for most of the sources. However, complex variability patterns that are not reflected contemporaneously in both energy bands were also detected, thereby providing tantalizing clues about the underlying radiative mechanisms. These results open up a new dimension to unravel the VHE emission processes operating in relativistic jets, hence sowing the seeds for their future observations with the upcoming Cherenkov Telescope Array.
While various methods have been proposed to disentangle the progenitor system for Type Ia supernovae, their origin is still unclear. Circumstellar environment is a key to distinguishing between the double-degenerate (DD) and single-degenerate (SD) scenarios since a dense wind cavity is expected only in the case of the SD system. We perform spatially resolved X-ray spectroscopy of Tycho's supernova remnant (SNR) with XMM-Newton and reveal the three-dimensional velocity structure of the expanding shock-heated ejecta measured from Doppler-broadened lines of intermediate-mass elements. Obtained velocity profiles are fairly consistent with those expected from a uniformly expanding ejecta model near the center, whereas we discover a rapid deceleration ($\sim4000$ km s$^{-1}$ to $\sim1000$ km s$^{-1}$) near the edge of the remnant in almost every direction. The result strongly supports the presence of a dense wall entirely surrounding the remnant, which is confirmed also by our hydrodynamical simulation. We thus conclude that Tycho's SNR is likely of the SD origin. Our new method will be useful for understanding progenitor systems of Type Ia SNRs in the era of high-angular/energy resolution X-ray astronomy with microcalorimeters.
We present an extensive analysis of the optical and UV properties of AT2023clx, the closest TDE to date, that occurred in the nucleus of the interacting LINER galaxy, NGC3799 (z=0.01107). From several standard methods, we estimate the mass of the central SMBH to be ~ 10^6 Msol. After correcting for the host reddening (E(B-V) = 0.177 mag) we measured its peak absolute g-band magnitude to be -18.25\pm0.05 mag, and its peak bolometric luminosity to be L_pk=(3.24\pm0.36)x10^43erg/s, making AT2023clx an intermediate luminosity TDE. The first distinctive feature of AT2023clx is that it rose to peak within only 10.4\pm2.5 days, making it the fastest rising TDE to date. Our SMBH mass estimate rules out the possibility of an intermediate mass BH as the reason of the fast rise. Dense spectral follow-up revealed a blue continuum that cools slowly and broad Balmer and HeII lines as well as weak HeI emission, features that are typically seen in TDEs. A flat Balmer decrement (~ 1.58) suggests that the lines are collisionally excited rather than being produced via photoionisation, as in typical active galactic nuclei. A second distinctive feature, seen for the first time in TDE spectra, is a sharp, narrow emission peak at a rest wavelength of ~6353 A. This feature is clearly visible up to 10d post-peak; we attribute it to clumpy material preceding the bulk outflow, and manifested as a high-velocity component of Ha (-9584km/s). The third distinctive feature is a break observed in the near-UV light curves that is reflected as a dip in the temperature evolution around ~18-28 days post-peak. Combining these findings, we propose a scenario for AT2023clx involving the disruption of a very low-mass star (<=0.1Msol) with an outflow launched in our line-of-sight with disruption properties that led to circularisation and prompt and efficient accretion disc formation, observed through a low-density photosphere.
The short Gamma Ray Bursts (GRBs) are the aftermath of the merger of binary compact objects (neutron star -- neutron star or neutron star -- black hole systems). With the simultaneous detection of Gravitational Wave (GW) signal from GW 170817 and GRB 170817A, the much-hypothesized connection between GWs and short GRBs has been proved beyond doubt. The resultant product of the merger could be a millisecond magnetar or a black hole depending upon the binary masses and their equation of state. In the case of a magnetar central engine, fraction of the rotational energy deposited to the emerging ejecta produces late time synchrotron radio emission from the interaction with the ambient medium. In this paper, we present an analysis of a sample of short GRBs located at a redshift of $z \leq 0.16$ which were observed at the late time to search for the emission from merger ejecta. Our sample consists of 7 short GRBs which have radio upper limits available from VLA and ATCA observations. We generate the model lightcurves using the standard magnetar model incorporating the relativistic correction. Using the model lightcurves and upper limits we constrain the number density of the ambient medium to be $10^{-5} - 10^{-3} cm^{-3}$ for rotational energy of the magnetar $E_{rot} \sim 5\times10^{51}$ erg. Variation of ejecta mass does not play a significant role in constraining the number density.
We study the emission of gravitational waves from spheroidal magnetized strange stars for both an isolated slowly rotating star and a binary system. In the first case, we compute the quadrupole moment and the amplitude of gravitational waves that may be emitted. For the binary system, the tidal deformability is obtained by solving simultaneously the system of spheroidal structure equations and the Love number equation. These results are compared with the data inferred from the GW170817 event which is also used to calculate the mass and tidal deformability of the companion star in the binary system. Our model supports binary systems formed by magnetized strange stars describing reasonable signals of gravitational waves contrasted with other models of binary systems composed of magnetized hadronic stars and non-magnetized quark stars.
Low-mass X-ray binaries (LMXBs) are high-energy sources that require multi-wavelength follow up campaigns to be fully characterized. New transients associated to LMXBs are regularly discovered, and previously known systems are often revisited by astronomers to constrain their intrinsic parameters. All of this information compiled into a catalogue may build up to a useful tool for subsequent studies on LMXBs and their population. We provide an update on past LMXB catalogues dating back 16 years and propose to the community a database on Galactic LMXBs with the most complete manually curated set of parameters and their original references. On top of a fixed version accessible through Vizier, we propose to host the catalogue independently on our GitHub collaboration, side-by-side with our previous catalogue on high-mass X-ray binaries. The database will be regularly updated based on new publications and community inputs. We build a working base by cross-matching previous LMXB catalogues and supplementing them with lists of hard X-ray sources detected in the past 20 years. We compile information from Simbad on LMXBs as a starting point for a thorough, manual search in the literature to retrieve important parameters that characterize LMXBs. We retrieve newly detected LMXBs and candidates directly from literature searches. Counterparts to these LMXBs are compiled from hard X-rays to infrared and radio domains. Every piece of information presented on the LMXBs is curated and backed by accurate references. We present a catalogue of 339 Galactic LMXBs listing their coordinates, companion star spectral type, systemic radial velocity, component masses and compact object nature, the presence of type I X-ray bursts as well as orbital data. Coordinates and identifiers of counterparts at various wavelengths are given, including 140 LMXBs detected in {\it Gaia} DR3.
Name that Neutrino is a citizen science project where volunteers aid in classification of events for the IceCube Neutrino Observatory, an immense particle detector at the geographic South Pole. From March 2023 to September 2023, volunteers did classifications of videos produced from simulated data of both neutrino signal and background interactions. Name that Neutrino obtained more than 128,000 classifications by over 1,800 registered volunteers that were compared to results obtained by a deep neural network machine-learning algorithm. Possible improvements for both Name that Neutrino and the deep neural network are discussed.
IceTop is the square kilometer surface array for cosmic-ray air showers of the IceCube Neutrino Observatory at the South Pole. IceTop consists of 81 stations, each comprised of a pair of ice-Cherenkov tanks, which over the years loses sensitivity due to snow coverage. This motivated the plan to enhance IceTop by the deployment of elevated scintillation panels and radio antennas. Coincident detection of an air shower with the IceTop tanks, the scintillators, and the antennas will increase the measurement accuracy of the cosmic-ray properties. While the radio antennas of the enhancement have a higher sensitivity to inclined showers, the current IceTop trigger, requiring coincident hits of both tanks of a station, loses efficiency for such showers. Therefore, we studied the feasibility of adding a trigger based on the multiplicity of single tank hits and studied its performance with simulations and data including a one-day test run at the South Pole. In this paper, we present the plans for the surface enhancement and the studies for the new IceTop trigger.
We report on multiwavelength studies of the blazar NVSS J171822+423948, which is identified as the low-energy counterpart of 4FGL J1718.5+4237, the only gamma-ray source known to be cospatial with the IceCube neutrino event IC-201221A. After a 12-year long quiescent period undetected by Fermi-LAT, gamma-ray activities with a tenfold flux increase emerge soon (a few tens of days) after arrival of the neutrino. Associated optical flares in the ZTF $g$, $r$, and $i$ bands are observed together with elevated WISE infrared fluxes. Synchronized variations suggest that both the gamma-ray emission and the neutrino event are connected to the blazar. Furthermore, the optical spectrum reveals emission lines at a redshift $z$ = 2.68 $\pm$ 0.01. Thus, it is the first candidate for a neutrino-emitting blazar at the redshift above 2. Discussions of theoretical constraints of neutrino production and comparisons with other candidates are presented.
Over recent decades, robotic (or highly automated) searches for supernovae (SNe) have discovered several thousand events, many of them in quite nearby galaxies (distances < 30 Mpc). Most of these SNe, including some of the best-studied events to date, were found before maximum brightness and have associated with them extensive follow-up photometry and spectroscopy. Some of these discoveries are so-called SN impostors, thought to be superoutbursts of luminous blue variable stars, although possibly a new, weak class of massive-star explosions. We conducted a Snapshot program with the Hubble Space Telescope(HST) and obtained images of the sites of 31 SNe and four impostors, to acquire late-time photometry through two filters. The primary aim of this project was to reveal the origin of any lingering energy for each event, whether it is the result of radioactive decay or, in some cases, ongoing late-time interaction of the SN shock with pre-existing circumstellar matter, or the presence of a light echo. Alternatively, lingering faint light at the SN position may arise from an underlying stellar population (e.g., a host star cluster, companion star, or a chance alignment). The results from this study complement and extend those from Snapshot programs by various investigators in previous HST cycles.
Cataclysmic Variables (CVs) are semi-detached binaries composed of a white dwarf orbiting a lower-mass K or M star. We investigate whether CVs are responsible for a new intriguing feature (the `hook') that appears in the Gaia DR3 colour-magnitude Hertzsprung-Russell diagram (HRD) when selecting sources with low extinction. We also aim to understand the location of CVs in the HRD based on the predictions of the disc instability model (DIM). The DIM is the foundation on which rests our basic understanding of stable (novae-like) and outbursting CVs (dwarf novae). We calculate the expected behaviour of CVs in the Gaia HRD taking into account the variable light contributed by the accretion disc, the companion, the white dwarf, and from the bright spot where the Roche lobe overflow stream from the companion intersects the disc. We find that the `hook' feature is most likely to be composed of CVs. The `hook' corresponds to the limited region where stable CVs (novae-likes) must be located in the HRD according to the DIM, with the bluest systems having the shortest orbital period. Unstable systems, giving rise to dwarf novae outbursts, trace counterclockwise loops in the HRD. The overall behaviour is consistent with the location of the various CV subtypes in the HRD. These results can be used as a basis to pinpoint interesting outliers in the HRD, either due to their location or their tracks. These outliers may signal new subtypes such as cold, stable CVs with truncated discs, or may challenge the disc instability model.
Short gamma-ray bursts (GRBs) are the aftermath of compact binary mergers involving neutron stars. If the merger remnant is a millisecond magnetar instead of a black hole, a significant proportion of the rotational energy deposited to the emerging ejecta can produce a late-time radio brightening from its interaction with the ambient medium. Detection of this late-time radio emission from short GRBs can have profound implications for understanding the physics of the progenitor. We report the radio observations of five short GRBs - 050709, 061210, 100625A, 140903A, and 160821B using the Giant Metrewave Radio Telescope (GMRT) at 1250, 610, and 325 MHz frequencies after $\sim$ $2 - 11$ years from the time of the burst. The GMRT observations at low frequencies are particularly important to detect the signature of merger ejecta emission at the peak. These observations are the most delayed searches associated with some of these GRBs for any late-time low-frequency emission. We find no evidence for such an emission. We find that none of these GRBs are consistent with maximally rotating magnetar with a rotational energy of $\sim 10^{53}\, {\rm ergs}$. However, magnetars with lower rotational energies cannot be completely ruled out. Despite the non detection, our study underscores the power of radio observations in the search for magnetar signatures associated with short GRBs. However, only future radio observatories may have the capabilities to either detect these signatures or put more stringent constraints on the model.
Some quasi-thermal (QT) dominated gamma-ray bursts (GRBs) could be well described by a multi-color blackbody (BB) function or a combined model of BB plus non-thermal (NT) component. In this analysis, two QT radiation-dominated bursts with known emission properties (GRB 210610B likely from a hybrid jet, and GRB 210121A with a spectrum consistent with a non-dissipative photospheric emission from a pure hot fireball) are used to make a comparison between these two modelings. To diagnose the magnetization properties of the central engine, the `top-down' approach proposed by Gao \& Zhang is adopted. It is found that diagnoses based on these two modelings could provide similar conclusions qualitatively; however, the modeling with mBB (or mBB+NT) may give more reasonable physical explanations. This implies that impacts from the GRB jet structure and the geometrical broadening on the observed spectrum should be considered. However, conservatively, these methods may be not sensitive enough to distinguish between the pure hot fireball and a mildly magnetized hybrid jet. Some other information is necessary to provide more evidence for the determination of jet properties for similar GRBs. Based on these considerations, we suggest that the photospheric emission of GRB 221022B is from a hot jet; a dissipation is caused by a internal shock (IS) mechanism due to the increasing Lorentz Factor with time, which makes its prompt emission behaves a typical evolution from thermal to NT.
Globular clusters (GCs) are particularly efficient at forming millisecond pulsars. Among these pulsars, about half lack a companion star, a significantly higher fraction than in the Galactic field. This fraction increases further in some of the densest GCs, especially those that have undergone core collapse, suggesting that dynamical interaction processes play a key role. For the first time, we create N-body models that reproduce the ratio of single-to-binary pulsars in Milky-Way-like GCs. We focus especially on NGC 6752, a typical core-collapsed cluster with many observed millisecond pulsars. Previous studies suggested that an increased rate of neutron star binary disruption in the densest clusters could explain the overabundance of single pulsars in these systems. Here, we demonstrate that binary disruption is ineffective and instead we propose that two additional dynamical processes play the dominant role: (1) tidal disruption of main-sequence stars by neutron stars; and (2) gravitational collapse of heavy white-dwarf-binary merger remnants. Neutron stars formed through these processes may also be associated with fast radio bursts similar to those observed recently in an extragalactic GC.
We interpret the peculiar super-solar nitrogen abundance recently reported by the James Webb Space Telescope observations for GN-z11 ($z=10.6$) using our state-of-the-art chemical evolution models. The observed CNO ratios can be successfully reproduced -- independently of the adopted initial mass function, nucleosynthesis yields, and presence of supermassive ($>$1000$M_\odot$) stars -- if the galaxy has undergone an intermittent star formation history with a quiescent phase lasting $\sim$100 Myr, separating two strong starbursts. Immediately after the second burst, Wolf--Rayet stars (up to $120M_\odot$) become the dominant enrichment source, also temporarily ($<$1 Myr) enhancing particular elements (N, F, Na, and Al) and isotopes ($^{13}$C and $^{18}$O). Alternative explanations involving (i) single burst models, also including very massive stars and/or pair-instability supernovae, or (ii) pre-enrichment scenarios fail to match the data. Feedback-regulated, intermittent star formation might be common in early systems. Elemental abundances can be used to test this hypothesis and to get new insights on nuclear and stellar astrophysics.
Using analytical tools from linear response theory, we systematically assess the accuracy of several microscopic derivations of Israel-Stewart hydrodynamics near local equilibrium. This allows us to "rank" the different approaches in decreasing order of accuracy as follows: Inverse Reynolds Dominance (IReD), Denicol-Niemi-Moln\'ar-Rischke (DNMR), second-order gradient expansion, and 14-moment approximation. We find that IReD theory is far superior to Navier-Stokes, being very accurate both in the asymptotic regime (i.e., for slow processes) and in the transient regime (i.e., on timescales comparable to the relaxation time). Also, the high accuracy of DNMR is confirmed, but neglecting second-order terms in the Knudsen number, which would render the equations parabolic, introduces serious systematic errors. Finally, in most cases, the second-order gradient expansion (a.k.a. non-resummed BRSSS) is found to be more inaccurate than Navier-Stokes in the transient regime. Overall, this analysis shows that Israel-Stewart hydrodynamics is falsifiable, and the relaxation time is observable, shedding new light on the debate on the viability of transient hydrodynamics as a well-defined physical theory distinguished from Navier-Stokes.
The sensitivity of current and future neutrino detectors like Super-Kamiokande (SK), JUNO, Hyper-Kamiokande (HK), and DUNE is expected to allow for the detection of the diffuse supernova neutrino background (DSNB). However, the DSNB model ingredients like the core-collapse supernova (CCSN) rate, neutrino emission spectra, and the fraction of failed supernovae are not precisely known. We quantify the uncertainty on each of these ingredients by (i) compiling a large database of recent star formation rate density measurements, (ii) combining neutrino emission from long-term axisymmetric CCSNe simulations and strategies for estimating the emission from the protoneutron star cooling phase, and (iii) assuming different models of failed supernovae. Finally, we calculate the fluxes and event rates at multiple experiments and perform a simplified statistical estimate of the time required to significantly detect the DSNB at SK with the gadolinium upgrade and JUNO. Our fiducial model predicts a flux of $5.1\pm0.4^{+0.0+0.5}_{-2.0-2.7}\,{\rm cm^2~s^{-1}}$ at SK employing Gd-tagging, or $3.6\pm0.3^{+0.0+0.8}_{-1.6-1.9}$ events per year, where the errors represent our uncertainty from star formation rate density measurements, uncertainty in neutrino emission, and uncertainty in the failed-supernova scenario. In this fiducial calculation, we could see a $3\sigma$ detection by $\sim2030$ with SK-Gd and a $5\sigma$ detection by $\sim2035$ with a joint SK-Gd/JUNO analysis, but background reduction remains crucial.
Firmamento (https://firmamento.hosting.nyu.edu) is a new-concept web-based and mobile-friendly data analysis tool dedicated to multi-frequency/multi-messenger emitters, as exemplified by blazars. Although initially intended to support a citizen researcher project at New York University-Abu Dhabi (NYUAD), Firmamento has evolved to be a valuable tool for professional researchers due to its broad accessibility to classical and contemporary multi-frequency open data sets. From this perspective Firmamento facilitates the identification of new blazars and other multi-frequency emitters in the localisation uncertainty regions of sources detected by current and planned observatories such as Fermi-LAT, Swift , eROSITA, CTA, ASTRI Mini-Array, LHAASO, IceCube, KM3Net, SWGO, etc. The multi-epoch and multi-wavelength data that Firmamento retrieves from over 90 remote and local catalogues and databases can be used to characterise the spectral energy distribution and the variability properties of cosmic sources as well as to constrain physical models. Firmamento distinguishes itself from other online platforms due to its high specialization, the use of machine learning and other methodologies to characterise the data and for its commitment to inclusivity. From this particular perspective, its objective is to assist both researchers and citizens interested in science, strengthening a trend that is bound to gain momentum in the coming years as data retrieval facilities improve in power and machine learning/artificial intelligence tools become more widely available
Recent inference results of the sound velocity in the cores of neutron stars are summarized. Implications for the equation of state and the phase structure of highly compressed baryonic matter are discussed. In view of the strong constraints imposed by the heaviest known pulsars, the equation of state must be very stiff in order to ensure the stability of these extreme objects. This required stiffness limits the possible appearance of phase transitions in neutron star cores. For example, a Bayes factor analysis quantifies strong evidence for squared sound velocities $c_s^2 > 0.1$ in the cores of 2.1 solar-mass and lighter neutron stars. Only weak first-order phase transitions with a small phase coexistence density range $\Delta\rho/\rho < 0.2$ (at the 68\% level) in a Maxwell construction still turn out to be possible within neutron stars. The central baryon densities in even the heaviest neutron stars do not exceed five times the density of normal nuclear matter. In view of these data-based constraints, much discussed issues such as the quest for a phase transition towards restored chiral symmetry, and the active degrees of freedom in cold and dense baryonic matter, are reexamined.
The light-curve evolution of a supernova contains information of the exploding star. Early-time photometry of a variety of explosive transients, including Calcium-rich transients and type IIb/Ibc and IIP supernovae shows evidence for an early light curve peak as a result of the explosion's shock wave passing through extended material (i.e., shock cooling emission (SCE)). Analytic modeling of the shock cooling emission allows us to estimate progenitor properties such as the radius and mass of extended material (e.g., the stellar envelope) as well as the shock velocity. In this work, we present a Python-based modular package that implements four analytic models originally developed in Piro 2015, Piro 2020 and Sapir & Waxman (2017) applied to photometric data to obtain progenitor parameter properties via different modeling techniques (including non-linear optimization, MCMC sampling). Our software is easily extendable to other analytic models for SCE and different methods of parameter estimation.
We report timing and spectral studies of the high mass X-ray binary 4U 1700-37 using Insight-HXMT observations carried out in 2020 during its out-of-eclipse state. We found significant variations in flux on a time-scale of kilo-seconds, while the hardness (count rate ratio between 10-30 keV and 2-10 keV) remains relatively stable. No evident pulsations were found over a frequency range of $10^{-3}$-2000 Hz. During the spectral analysis, for the first time we took the configuration of different Insight-HXMT detectors' orientations into account, which allows us obtaining reliable results even if a stable contamination exists in the field-of-view. We found that the spectrum could be well described by some phenomenological models that commonly used in accreting pulsars (e.g., a power law with a high energy cutoff) in the energy range of 2-100 keV. We found hints of cyclotron absorption features around ~ 16 keV or/and ~ 50 keV.
Variability studies of active galactic nuclei are a powerful diagnostic tool in understanding the physical processes occurring in disk-jet regions, unresolved by direct imaging with currently available techniques. Here, we report the first attempt to systematically characterize intra-night optical variability (INOV) for a sample of seven apparently radio-quiet narrow-line Seyfert 1 galaxies (RQNLSy1s) that had shown recurring flaring at 37 GHz in the radio observations at Metsahovi Radio Observatory (MRO), indicating the presence of relativistic jets in them, but no evidence for relativistic jets in the recent radio observations of Karl G. Jansky Very Large Array (JVLA) at 1.6, 5.2, and 9.0 GHz. We have conducted a total of 28 intra-night sessions, each lasting $\geq$ 3 hrs for this sample, resulting in an INOV duty cycle ($\overline{DC} ~\sim$20%) similar to that reported for $\gamma$-ray-NLSy1s (DC $\sim$25% - 30%), that display blazar-like INOV. This in turn infers the presence of relativistic jet in our sample sources. Thus, it appears that even lower-mass (M$_{BH} \sim$10$^{6}$ M$_{\odot}$) RQNLSy1 galaxies can maintain blazar-like activities. However, we note that the magnetic reconnection in the magnetosphere of the black hole can also be a viable mechanism to give rise to the INOV from these sources.
We present the results of an ultra-deep radio continuum survey, containing $\sim480$ hours of observations, of the Galactic globular cluster 47 Tucanae with the Australia Telescope Compact Array. This comprehensive coverage of the cluster allows us to reach RMS noise levels of 1.19 $\mu Jy~\textrm{beam}^{-1}$ at 5.5 GHz, 940 $nJy~\textrm{beam}^{-1}$ at 9 GHz, and 790 $nJy~\textrm{beam}^{-1}$ in a stacked 7.25 GHz image. This is the deepest radio image of a globular cluster, and the deepest image ever made with the Australia Telescope Compact Array. We identify ATCA J002405.702-720452.361, a faint ($6.3\pm1.2$ $\mu Jy$ at 5.5 GHz, $5.4\pm0.9$ $\mu Jy$ at 9 GHz), flat-spectrum ($\alpha=-0.31\pm0.54$) radio source that is positionally coincident with the cluster centre and potentially associated with a faint X-ray source. No convincing optical counterpart was identified. We use radio, X-ray, optical, and UV data to show that explanations involving a background active galactic nucleus, a chromospherically active binary, or a binary involving a white dwarf are unlikely. The most plausible explanations are that the source is an undiscovered millisecond pulsar or a weakly accreting black hole. If the X-ray source is associated with the radio source, the fundamental plane of black hole activity suggests a black hole mass of $\sim54-6000$ M$_{\odot}$, indicating an intermediate-mass black hole or a heavy stellar-mass black hole.
A new mechanism is proposed to account for the formation of retrograde hot Jupiter in coplanar star-planet system via close encounter between a Jupiter mass planet and a brown dwarf mass planet. After long timescale scattering between several Jupiter mass planets with inner orbits, the remaining planets still rotating around the star could have large semimajor with large eccentricity. If there exists a brown dwarf mass planet in distant orbit around the star, planetary encounter may happen. After encounter, the Jupiter mass planet may rotate around the star in a retrograde orbit with extremely large eccentricity and the periastron can reach about 0.01 AU, which means that, within the first several orbits around the star, tidal interaction from the star can shrink the semimajor axis of the planet quickly. Thus, the Jupiter mass planet is isolated from the brown dwarf mass planet due to the quick decrease of its apastron distance and eventually evolves into a retrograde hot Jupiter.
Pulsar Timing Array (PTA) experiments worldwide recently reported evidence of a nHz stochastic gravitational wave background (sGWB) compatible with the existence of slowly inspiralling massive black hole (MBH) binaries (MBHBs). The shape of the signal contains valuable information about the evolution of $z<1$ MBHs above $\rm 10^8 M_{\odot}$, suggesting a faster dynamical evolution of MBHBs towards the gravitational-wave-driven inspiral or a larger MBH growth than usually assumed. In this work, we investigate if the nHz sGWB could also provide constraints on the population of merging lower-mass MBHBs ($\rm {<} 10^7 \, M_{\odot}$) detectable by LISA. To this end, we use the $\texttt{L-Galaxies}$ semi-analytical model applied to the $\texttt{Millennium}$ suite of simulations. We generate a population of MBHs compatible simultaneously with current electromagnetic and nHz sGWB constraints by including the possibility that, in favourable environments, MBHs can accrete gas beyond the Eddington limit. The predictions of the model show that the global (integrated up to high-$z$) LISA detection rate is {\it not} significantly affected when compared to a fiducial model whose nHz sGWB signal is ${\sim}\,2$ times smaller. In both cases, the global rate yields ${\sim}\,12 \rm yr^{-1}$ and is dominated by systems of $\rm 10^{5-6} M_{\odot}$. The main differences are limited to low-$z$ ($z<3$), high-mass (${>}\rm 10^6\, M_{\odot}$) LISA MBHBs. The model compatible with the latest PTA results predicts up to ${\sim}\,1.6$ times more detections, with a rate of ${\sim}1\rm yr^{-1}$. We find that these LISA MBHB systems have 50\% probability of shining with bolometric luminosities $>10^{43}\rm erg/s$. Hence, in case PTA results are confirmed and given the current MBH modelling, our findings suggest there will be higher chances to perform multimessenger studies with LISA MBHB than previously expected.
Resolving the environments of massive stars is crucial for understanding their formation mechanisms and their impact on galaxy evolution. An important open question is whether massive stars found in diffuse regions outside spiral arms formed in-situ or migrated there after forming in denser environments. To address this question, we use multi-resolution measurements of extinction in the Andromeda Galaxy (M31) to probe the ISM surrounding massive stars across galactic environments. We construct a catalog of 42,107 main-sequence massive star candidates ($M \geq 8 M_{\odot}$) using resolved stellar photometry from the Panchromatic Hubble Andromeda Treasury (PHAT) program, plus stellar and dust model fits from the Bayesian Extinction and Stellar Tool (BEAST). We quantify galactic environments by computing surrounding stellar densities of massive stars using Kernel Density Estimation. We then compare high-resolution line-of-sight extinction estimates from the BEAST with 25-pc resolution dust maps from PHAT, measuring the total column density distribution of extinction. Our key finding is that, although the average total column density of dust increases with the density of massive stars, the average line-of-sight extinction towards massive stars remains constant across all environments. This suggests that massive stars have a uniform amount of dust in their immediate environment, regardless of their location in the galaxy. One possible explanation for these findings is that small molecular clouds are still capable of forming massive stars, even if they are not resolvable at 25-pc. These results indicate that massive stars are forming in the sparse regions of M31, as opposed to migrating there.
We use simulated attenuation curves from the NIHAO-SKIRT-Catalog to test the flexibility of commonly used dust attenuation models in the face of the variations expected from realistic star-dust geometries. Motivated by lack of flexibility in these existing models, we propose a novel dust attenuation model with three free parameters that can accurately recover the simulated attenuation curves as well as the best-fitting curves from the commonly used models. This new model is fully analytic and treats all starlight equally, in contrast to two-component dust attenuation models. We use the parametrization to investigate the relationship between the overall attenuation law shape and the strength of the 2175 \AA\ bump. Our results indicate variation in star-dust geometry leads these features to correlate tightly, with grayer attenuation curves having weaker bumps.
We present new radio continuum images and a source catalogue from the MeerKAT survey in the direction of the Small Magellanic Cloud (SMC). The observations, at a central frequency of 1.3 GHz across a bandwidth of 0.8 GHz, encompass a field of view ~7 x 7 degrees and result in images with resolution of 8 arcsec. The median broad-band Stokes I image Root Mean Squared noise value is ~11 microJy/beam. The catalogue produced from these images contains 108,330 point sources and 517 compact extended sources. We also describe a UHF (544-1088 MHz) single pointing observation. We report the detection of a new confirmed Supernova Remnant (SNR) (MCSNR J0100-7211) with an X-ray magnetar at its centre and 10 new SNR candidates. This is in addition to the detection of 21 previously confirmed SNRs and two previously noted SNR candidates. Our new SNR candidates have typical surface brightness an order of magnitude below those previously known, and on the whole they are larger. The high sensitivity of the MeerKAT survey also enabled us to detect the bright end of the SMC Planetary Nebulae (PNe) sample - point-like radio emission is associated with 38 of 102 optically known PNe, of which 19 are new detections. Lastly, we present the detection of three foreground radio stars amidst 11 circularly polarised sources, and a few examples of morphologically interesting background radio galaxies from which the radio ring galaxy ESO 029-G034 may represent a new type of radio object.
We present results from conducting a theoretical chemical analysis of a sample of benchmark companion brown dwarfs whose primary star is of type F, G or K. We summarize the entire known sample of these types of companion systems, termed "compositional benchmarks", that are present in the literature or recently published as key systems of study in order to best understand brown dwarf chemistry and condensate formation. Via mass balance and stoichiometric calculations, we predict a median brown dwarf atmospheric oxygen sink of $17.8^{+1.7}_{-2.3}\%$ by utilizing published stellar abundances in the local solar neighborhood. Additionally, we predict a silicate condensation sequence such that atmospheres with bulk Mg/Si $\lesssim$ 0.9 will form enstatite (MgSiO$_3$) and quartz (SiO$_2$) clouds and atmospheres with bulk Mg/Si $\gtrsim$ 0.9 will form enstatite and forsterite (Mg$_2$SiO$_4$) clouds. Implications of these results on C/O ratio trends in substellar mass objects and utility of these predictions in future modeling work are discussed.
Spectrophotometric data of the young planetary nebula M 3-27, from 2004 to 2021, are presented and discussed. We corroborate that the H I Balmer lines present features indicating they are emitted by the central star, therefore He I lines were used to correct line fluxes by effects of reddening. Important variability on the nebular emission lines between 1964 to 2021, probably related to density changes in the nebula, is reported. Diagnostic diagrams to derive electron temperatures and densities have been constructed. The nebula shows a very large density contrast with an inner density of the order of 10$^{7}$ cm$^{-3}$ and an outer density of about $10^3 - 10^4$ cm$^{-3}$. With these values of density, electron temperatures of $16,000 - 18,000$ K have been found from collisionally excited lines. Due to the central star emits in the H$^+$ lines, ionic abundances relative to He$^+$ were calculated from collisionally excited and recombination lines, and scaled to H$^+$ by considering that He$^+$/H$^+$ $=$ He/H$ = 0.11$. ADF(O$^{+2}$) values were also determined. Total abundance values obtained indicate sub-solar abundances, similarly to what is found in other comparable objects like IC 4997.
Using the integral field spectroscopic data from Mapping Nearby Galaxies at Apache Point Observatory survey, we study the kinematics and stellar population properties of the two counter-rotating stellar disks in a nearby galaxy SDSS J074834.64+444117.8. We disentangle the two stellar disks by three methods, including CaII $\lambda$8542 double Gaussian fit, pPXF spectral decomposition, and orbit-based dynamical model. These three different methods give consistent stellar kinematics. The pPXF spectral decomposition provides the spectra of two stellar disks, with one being more luminous across the whole galaxy named primary disk, and the other named secondary disk. The primary disk is counter-rotating with ionized gas, while the secondary disk is co-rotating with ionized gas. The secondary disk has younger stellar population and poorer stellar metallicity than the primary disk. We estimate the stellar mass ratio between the primary and secondary disks to be $\sim$5.2. The DESI $g$, $r$, $z$ color image doesn't show any merger remnant feature in this galaxy. These findings support a scenario that the counter-rotating stellar disks in SDSS J074834.64+444117.8 formed through gas accretion from the cosmic web or a gas-rich companion.
Dusty plasma which is nothing but an admixture of electrons, ions and massive charged solid particles of sub-micron to micron sized in the background of neutrals. The dust grain medium exhibits fluid as well as solid-like characteristics depending on the background medium conditions. It supports various self-sustained non-linear dynamical structures as a result of the saturation of instabilities. The vortical or vortex structure in the dusty plasma medium is one of self-sustained dynamical structures that are formed either by internal instabilities or external perturbation. In this review report, the author discusses the theoretical, experimental, and computational research works on vortical and coherent structures in unmagnetized as well as in magnetized dusty plasma. The sources of vortex formation such as obstacle, ion drag shear, dust charge gradient, RT and K-H instabilities are pointed out in detail. The studies on the evolution of vortices by researchers are also discussed.
The relevance of some galactic feedback mechanisms, in particular cosmic ray feedback and the hydrogen ionizing radiation field, has been challenging to definitively describe in a galactic context, especially far outside the galaxy in the circumgalactic medium (CGM). Theoretical and observational uncertainties prevent conclusive interpretations of multiphase CGM properties derived from ultraviolet (UV) diagnostics. We conduct three dimensional magnetohydrodynamic simulations of a section of a galactic disk with star formation and feedback, including radiative heating from stars, a UV background, and cosmic ray feedback. We utilize the temperature phases present in our simulations to generate Cloudy models to derive spatially and temporally varying synthetic UV diagnostics. We find that radiative effects \hl{without additional heating mechanisms} are not able to produce synthetic diagnostics in the observed ranges. For low cosmic ray diffusivity $\kappa_{\rm{cr}}=10^{28} \rm{cm}^2 \rm{s}^{-1}$, cosmic ray streaming heating in the outflow helps our synthetic line ratios roughly match observed ranges by producing transitional temperature gas ($T \sim 10^{5-6}$ K). High cosmic ray diffusivity $\kappa_{\rm{cr}}=10^{29} \rm{cm}^2 \rm{s}^{-1}$, with or without cosmic ray streaming heating, produced transitional temperature gas. The key parameter controlling the production of this gas phase remains unclear, as the different star formation history and outflow evolution itself influences these diagnostics. Our work demonstrates the use of UV plasma diagnostics to differentiate between galactic/circumgalactic feedback models.
With its sensitivity in the rest-frame optical, the James Webb Space Telescope (JWST) has uncovered active galactic nuclei (AGN), comprising both intrinsically faint and heavily reddened sources, well into the first billion years of the Universe, at $z \sim 4-11$. In this work, we revisit the AGN contribution to reionization given the high number densities associated with these objects. We use the DELPHI semi-analytic model, base-lined against the latest high-redshift datasets from the JWST and the Atacama Large millimetre Array (ALMA) to model early star forming galaxies and AGN. We calculate the escape fractions of ionizing radiation from both star formation and AGN and include the impact of reionization feeback in suppressing the baryonic content of low-mass galaxies in ionized regions. This model is validated against the key observables for star forming galaxy, AGN and reionization. In our {\it fiducial} model, reionization reaches its mid-point at $z \sim 6.9$ and ends by $z \sim 5.9$. Low stellar mass ($M_*\leq 10^9M_\odot$) star forming galaxies are found to be the key drivers of the reionization process, providing about $77\%$ of the total photon budget. Despite their high numbers, high accretion rates and higher escape fractions compared to star forming galaxies at $z \sim 5$, AGN only provide about $23\%$ of the total reionization budget which is dominated by black holes in high stellar mass systems (with $M_* \geq 10^9M_\odot$). This is because AGN number densities become relevant only at $z \leq 7$ - as a result, AGN contribute as much as galaxies as late as $z \sim 6.2$, when reionization is already in its end stages. Finally, we find that even contrasting models of the AGN ionizing photon escape fraction (increasing or decreasing with stellar mass) do not qualitatively change our results.
The Large Magellanic Cloud (LMC) is the Milky Way's most massive satellite galaxy, which only recently (~2 billion years ago) fell into our Galaxy. Since stellar atmospheres preserve their natal cloud's composition, the LMC's recent infall makes its most ancient, metal-deficient ("low-metallicity") stars unique windows into early star formation and nucleosynthesis in a formerly distant region of the high-redshift universe. Previously, identifying such stars in the LMC was challenging. But new techniques have opened this window, now enabling tests of whether the earliest element enrichment and star formation in distant, extragalactic proto-galaxies deviated from what occurred in the proto-Milky Way. Here we present the elemental abundances of 10 stars in the LMC with iron-to-hydrogen ratios ranging from ~1/300th to ~1/12,000th of the Sun. Our most metal-deficient star is 50 times more metal-deficient than any in the LMC with available detailed chemical abundance patterns, and is likely enriched by a single extragalactic first star supernova. This star lacks significant carbon-enhancement, as does our overall sample, in contrast with the lowest metallicity Milky Way stars. This, and other abundance differences, affirm that the extragalactic early LMC experienced diverging enrichment processes compared to the early Milky Way. Early element production, driven by the earliest stars, thus appears to proceed in an environment-dependent manner.
We analyze the anomalies appearing in the light curves of the three microlensing events MOA-2022-BLG-563, KMT-2023-BLG-0469, and KMT-2023-BLG-0735. The anomalies exhibit common short-term dip features that appear near the peak. From the detailed analyses of the light curves, we find that the anomalies were produced by planets accompanied by the lenses of the events. For all three events, the estimated mass ratios between the planet and host are on the order of $10^{-4}$: $q\sim 8 \times 10^{-4}$ for MOA-2022-BLG-563L, $q\sim 2.5\times 10^{-4}$ for KMT-2023-BLG-0469L, and $q\sim 1.9\times 10^{-4}$ for KMT-2023-BLG-0735L. The interpretations of the anomalies are subject to a common inner-outer degeneracy, which causes ambiguity when estimating the projected planet-host separation. We estimated the planet mass, $M_{\rm p}$, host mass, $M_{\rm h}$, and distance, $D_{\rm L}$, to the planetary system by conducting Bayesian analyses using the observables of the events. The estimated physical parameters of the planetary systems are $(M_{\rm h}/M_\odot, M_{\rm p}/M_{\rm J}, D_{\rm L}/{\rm kpc}) = (0.48^{+0.36}_{-0.30}, 0.40^{+0.31}_{-0.25}, 6.53^{+1.12}_{-1.57})$ for MOA-2022-BLG-563L, $(0.47^{+0.35}_{-0.26}, 0.124^{+0.092}_{-0.067}, 7.07^{+1.03}_{-1.19})$ for KMT-2023-BLG-0469L, and $(0.62^{+0.34}_{-0.35}, 0.125^{+0.068}_{-0.070}, 6.26^{+1.27}_{-1.67})$ for KMT-2023-BLG-0735L. According to the estimated parameters, all planets are cold planets with projected separations that are greater than the snow lines of the planetary systems, they have masses that lie between the masses of Uranus and Jupiter of the Solar System, and the hosts of the planets are main-sequence stars that are less massive than the Sun.
Dark matter is hypothetical matter believed to address the missing mass problem in galaxies. However, alternative theories, such as Modified Newtonian Dynamics (MOND), have been notably successful in explaining the missing mass problem in various astrophysical systems. The vertical distribution function of stars in the solar neighbourhood serves as a proxy to constrain galactic dynamics in accordance to its contents. We employ both the vertical positional and velocity distribution of stars in cylindrical coordinates with a radius of 150 pc and a half-height of 200 pc from the galactic plane. Our tracers consist of main-sequence A, F, and early-G stars from the GAIA, RAVE, APOGEE, GALAH, and LAMOST catalogues. We attempt to solve the missing mass in the solar neighbourhood, interpreting it as either dark matter or MOND. Subsequently, we compare both hypotheses newtonian gravity with dark matter and MOND, using the Bayes factor (BF) to determine which one is more favoured by the data. We found that the inferred dark matter in the solar neighbourhood is in range of $\sim (0.01$-$0.07)$ M$_{\odot}$ pc$^{-3}$. We also determine that the MOND hypothesis's acceleration parameter $a_0$ is $(1.26 \pm 0.13) \times 10^{-10}$ m s$^{-2}$ for simple interpolating function. The average of bayes factor for all tracers between the two hypotheses is $\log \textrm{BF}\sim 0.1$, meaning no strong evidence in favour of either the dark matter or MOND hypotheses.
Magnetic fields may play a crucial role in setting the initial conditions of massive star and star cluster formation. To investigate this, we report SOFIA-HAWC+ $214\:\mu$m observations of polarized thermal dust emission and high-resolution GBT-Argus C$^{18}$O(1-0) observations toward the massive Infrared Dark Cloud (IRDC) G28.37+0.07. Considering the local dispersion of $B$-field orientations, we produce a map of $B$-field strength of the IRDC, which exhibits values between $\sim0.03 - 1\:$mG based on a refined Davis-Chandrasekhar-Fermi (r-DCF) method proposed by Skalidis \& Tassis. Comparing to a map of inferred density, the IRDC exhibits a $B-n$ relation with a power law index of $0.51\pm0.02$, which is consistent with a scenario of magnetically-regulated anisotropic collapse. Consideration of the mass-to-flux ratio map indicates that magnetic fields are dynamically important in most regions of the IRDC. A virial analysis of a sample of massive, dense cores in the IRDC, including evaluation of magnetic and kinetic internal and surface terms, indicates consistency with virial equilibrium, sub-Alfv\'enic conditions and a dominant role for $B-$fields in regulating collapse. A clear alignment of magnetic field morphology with direction of steepest column density gradient is also detected. However, there is no preferred orientation of protostellar outflow directions with the $B-$field. Overall, these results indicate that magnetic fields play a crucial role in regulating massive star and star cluster formation and so need to be accounted for in theoretical models of these processes.
Hot Jupiters (HJ) are defined as Jupiter-mass exoplanets orbiting around their host star with an orbital period < 10 days. It is assumed that HJ do not form in-situ but ex-situ. Recent discoveries show that star clusters contribute to the formation of HJ. We present direct $N$-body simulations of planetary systems in star clusters and analyze the formation of HJ in them. We combine two direct $N$-body codes: NBODY6++GPU for the dynamics of dense star clusters with 32 000 and 64 000 stellar members and LonelyPlanets used to follow 200 identical planetary systems around solar mass stars in those star clusters. We use different sets with 3, 4, or 5 planets and with the innermost planet at a semi-major axis of 5 au or 1 au and follow them for 100 Myr in our simulations. The results indicate that HJs are generated with high efficiency in dense star clusters if the innermost planet is already close to the host star at a semi-major axis of 1 au. If the innermost planet is initially beyond a semi-major axis of 5 au, the probability of a potential HJ ranges between $1.5-4.5$ percent. Very dense stellar neighborhoods tend to eject planets rather than forming HJs. A correlation between HJ formation and angular momentum deficit (AMD) is not witnessed. Young Hot Jupiters ($t_{\rm age} < 100$ Myrs) have only been found, in our simulations, in planetary systems with the innermost planet at a semi-major axis of 1 au.
Radio data can give stringent constraints for annihilating dark matter. In general, radio observations can detect very accurate radio flux density with high resolution and different frequencies for nearby galaxies. We are able to obtain the radio flux density as a function of distance from the galactic center and frequencies $S(r,\nu)$. In this article, we demonstrate a comprehensive radio analysis of the M33 galaxy, combining the radio flux density profile $S(r)$ and the frequency spectrum $S(\nu)$ to get the constraints of dark matter annihilation parameters. By analyzing the archival radio data obtained from the Effelsberg telescope, we show that the dark matter annihilation contributing to the radio flux density might be insignificant in the disk region of the M33 galaxy. Moreover, by including the baryonic radio contribution, we constrain the $2\sigma$ conservative upper limits of the annihilation cross section, which can be complementary to the existing constraints based on neutrino, cosmic-ray, and gamma-ray observations. Our results indicate that analyzing the galactic multi-frequency radio flux profiles can give useful and authentic constraints on dark matter for the leptophilic annihilation channels.
Geometric distortion (GD) critically constrains the precision of astrometry. Some telescopes lack GD calibration observations, making it impossible to accurately determine the GD effect using well-established methods. This limits the value of telescope observations in certain astrometric scenarios, such as using historical observations of moving targets in the solar system to improve their orbit. We investigated a method for handling GD in the absence of calibration observations. This method requires only several frames with a dozen reference stars to derive an accurate GD solution, so that it can be used for solving GD of some telescopes which were intractable in the past. By using this GD solution, the astrometric precision of the historical observations obtained from these telescopes can be improved. We use the weighted average of the plate constants to derive the GD solution, which is implemented by Python language and released on GitHub. Then this method is applied to solve GD in the observations taken with the 60-cm, 1-m, and 2.4-m telescopes at Yunnan Observatory. The GD solutions are compared with those obtained using well-established methods to demonstrate the accuracy. Applications of our method in the reduction of observations for the moon of Jupiter (Himalia) and the binary GSC2038-0293 are presented as examples. After GD correction, the mean residual between observed and computed position ($O-C$) for the binary GSC2038-0293 decreased from 36 mas to 5 mas.
We present the first detection of HCNS (thiofulminic acid) in space with the QUIJOTE line survey in the direction of TMC-1. We performed a complete study of the isomers of CHNS and CHNO, including NCO and NCS. The derived column densities for HCNS, HNCS, and HSCN are (9.0+/-0.5)e9, (3.2+/-0.1)e11, and (8.3+/-0.4)e11 cm-2, respectively. The HNCS/HSCN abundance ratio is 0.38. The abundance ratios HNCO/HNCS, HCNO/HCNS, HOCN/HSCN, and NCO/NCS are 34+/-4, 8.3+/-0.7, 0.18+/-0.03, and 0.78+/-0.07, respectively. These ratios cannot be correctly reproduced by our gas-phase chemical models, which suggests that formation paths for these species are missing, and/or that the adopted dissociative recombination rates for their protonated precursors have to be revised. The isotopologues H15NCO, DNCO, N13CO, DCNO, H34SCN, and DSCN have also been detected with the ultrasensitive QUIJOTE line survey.
Long-term spectroscopic monitoring campaigns on active galactic nuclei (AGNs) provide a wealth of information about its interior structure and kinematics. However, a number of the observations suffer from the contamination of second-order spectra (SOS) which will introduce some undesirable uncertainties at the red side of the spectra. In this paper, we test the effect of SOS and propose a method to correct it in the time domain spectroscopic data using the simultaneously observed comparison stars. Based on the reverberation mapping (RM) data of NGC 5548 in 2019, one of the most intensively monitored AGNs by the Lijiang 2.4 m telescope, we find that the scientific object, comparison star, and spectrophotometric standard star can jointly introduce up to similar to 30% SOS for Grism 14. This irregular but smooth SOS significantly affects the flux density and profile of the emission line, while having little effect on the light curve. After applying our method to each spectrum, we find that the SOS can be corrected effectively. The deviation between corrected and intrinsic spectra is similar to 2%, and the impact of SOS on time lag is very minor. This method makes it possible to obtain the H alpha RM measurements from archival data provided that the spectral shape of the AGN under investigation does not have a large change.
The roles that mass and environment play in the galaxy quenching are still under debate. Leveraging the Photometric objects Around Cosmic webs (PAC) method, we analyze the excess surface distribution $\bar{n}_2w_{\rm{p}}(r_{\rm{p}})$ of photometric galaxies in different color (rest-frame $u-r$) within the stellar mass range of $10^{9.0}M_{\odot}\sim10^{11.0}M_{\odot}$ around spectroscopic massive central galaxies ($10^{10.9}\sim10^{11.7}M_{\odot}$) at the redshift interval $0<z_s<0.7$, utilizing data from the Hyper SuprimeCam Subaru Strategic Program and the spectroscopic samples of Slogan Digital Sky Survey (i.e. Main, LOWZ and CMASS samples). We find that both mass and environment quenching contribute to the evolution of companion galaxies. To isolate the environment effect, we quantify the quenched fraction excess (QFE) of companion galaxies encircling massive central galaxies within $0.01h^{-1}{\rm{Mpc}}<r_{\rm{p}}<20h^{-1}\rm{Mpc}$, representing the surplus quenched fraction relative to the average. We find that the high density halo environment affects the star formation quenching up to about three times of the virial radius, and this effect becomes stronger at lower redshift. We also find that even after being scaled by the virial radius, the environment quenching efficiency is higher for more massive halos or for companion galaxies of higher stellar mass, though the trends are quite weak. We present a fitting formula that comprehensively captures the QFE across central and companion stellar mass bins, halo-centric distance bins, and redshift bins, offering a valuable tool for constraining galaxy formation models. Furthermore, we have made a quantitative comparison with Illustris-TNG that underscores some important differences, particularly in the excessive quenching of low-mass companion galaxies ($<10^{9.5}M_{\odot}$) by TNG.
By combining spectra from the CALSPEC and NGSL, as well as spectroscopic data from the LAMOST Data Release 7 (DR7), we have analyzed and corrected the systematic errors of the Gaia DR3 BP/RP (XP) spectra. The errors depend on the normalized spectral energy distribution (simplified by two independent ``colors'') and $G$ magnitude. Our corrections are applicable in the range of approximately $-0.5<BP-RP<2$, $3<G<17.5$ and $E(B-V)<0.8$. To validate our correction, we conduct independent tests by comparing with the MILES and LEMONY spectra. The results demonstrate that the systematic errors of $BP-RP$ and $G$ have been effectively corrected, especially in the near ultraviolet. The consistency between the corrected Gaia XP spectra and the MILES and LEMONY is better than 2 per cent in the wavelength range of $336-400$\,nm and 1 per cent in redder wavelengths. A global absolute calibration is also carried out by comparing the synthetic Gaia photometry from the corrected XP spectra with the corrected Gaia DR3 photometry. Our study opens up new possibilities for using XP spectra in many fields. A Python package is publicly available to do the corrections (https://doi.org/10.12149/101375 or https://github.com/HiromonGON/GaiaXPcorrection).
We present rest-frame optical spectroscopy using JWST/NIRSpec IFU for the radio galaxy TN J1338-1942 at z=4.1, one of the most luminous galaxies in the early Universe with powerful extended radio jets. Previous observations showed evidence for strong, large-scale outflows on the basis of its large (~150 kpc) halo detected in Ly-alpha, and high velocity [O II] emission features detected in ground-based IFU data. Our NIRSpec/IFU observations spatially resolve the emission line properties across the host galaxy in great detail. We find at least five concentrations of line emission, coinciding with discrete continuum features previously detected in imaging from HST and JWST, over an extent of ~2'' (~15 kpc). The spectral diagnostics enabled by NIRSpec unambiguously trace the activity of the obscured AGN plus interaction between the interstellar medium and the radio jet as the dominant mechanisms for the ionization state and kinematics of the gas in the system. A secondary region of very high ionization lies at roughly 5 kpc distance from the nucleus, and within the context of an expanding cocoon enveloping the radio lobe, this may be explained by strong shock-ionization of the entrained gas. However, it could also signal the presence of a second obscured AGN, which may also offer an explanation for an intriguing outflow feature seen perpendicular to the radio axis. The presence of a dual SMBH system in this galaxy would support that large galaxies in the early Universe quickly accumulated their mass through the merging of smaller units (each with their own SMBH), at the centers of large overdensities. The inferred black hole mass to stellar mass ratio of 0.01-0.1 for TNJ1338 points to a more rapid assembly of black holes compared to the stellar mass of galaxies at high redshifts, consistent with other recent observations.
Theoretical models suggest the existence of a dark matter spike surrounding the supermassive black holes at the core of galaxies. The spike density is thought to obey a power law that starts at a few times the black hole horizon radius and extends to a distance, $R_\text{sp}$, of the order of a kiloparsec. We use the Tolman-Oppenheimer-Volkoff equations to construct the spacetime metric representing a black hole surrounded by such a dark matter spike. We consider the dark matter to be a perfect fluid, but make no other assumption about its nature. The assumed power law density provides in principle three parameters with which to work: the power law exponent $\gamma_\text{sp}$, the external radius $R_\text{sp}$, and the spike density $\rho_\text{DM}^\text{sp}$ at $R_\text{sp}$. These in turn determine the total mass of the spike. We focus on Sagittarius A* and M87 for which some theoretical and observational bounds exist on the spike parameters. Using these bounds in conjunction with the metric obtained from the Tolman-Oppenheimer-Volkoff equations, we investigate the possibility of detecting the dark matter spikes surrounding these black holes via the gravitational waves emitted at the ringdown phase of black hole perturbations. Our results suggest that if the spike to black hole mass ratio is roughly constant, greater mass black holes require relatively smaller spike densities to yield potentially observable signals. We find that is unlikely for the spike in M87 to be detected via the ringdown waveform with currently available techniques unless its mass is roughly an order of magnitude larger than existing observational estimates. However, given that the signal increases with black hole mass, spikes might be observable for more massive galactic black holes in the not too distant future.
During the epoch of reionisation the first galaxies were enshrouded in pristine neutral gas, with one of the brightest emission lines in star-forming galaxies, Lyman-$\alpha$ (Ly$\alpha$), expected to remain undetected until the Universe became ionised. Providing an explanation for the surprising detection of Ly$\alpha$ in these early galaxies is a major challenge for extra-galactic studies. Recent JWST observations have reignited the debate on whether residence in an overdensity of galaxies is a it sufficient and necessary condition for Ly$\alpha$ to escape. Here, we take unique advantage of both high-resolution and high-sensitivity images from the JWST instrument NIRCam to reveal that all galaxies in a sample of z>7 Ly$\alpha$ emitters have close companions. We exploit novel on-the-fly radiative transfer magnetohydrodynamical simulations with cosmic ray feedback to show that galaxies with frequent mergers have very bursty star formation which drives episodes of high intrinsic Ly$\alpha$ emission and facilitates the escape of Ly$\alpha$ photons along channels cleared of neutral gas. We conclude that the rapid build up of stellar mass through mergers presents a compelling solution to the long-standing puzzle of the detection of Ly$\alpha$ emission deep into the epoch of reionisation.
Recent results from spectroscopic and astrometric surveys of nearby stars suggest that the stellar disk of our Milky Way (MW) was formed quite early, within the first few billion years of its evolution. Chemokinematic signatures of disk formation in cosmological zoom-in simulations appear to be in tension with these data, implying that MW-like disk formation is delayed in simulations. We investigate the formation of galactic disks using a representative sample of MW-like galaxies from the cosmological-volume simulation TNG50. We find that on average MW-mass disks indeed form later than the local data suggest. However, their formation time and metallicity exhibit a substantial scatter, such that $\sim$10% of MW-mass galaxies form disks early, similar to the MW. Thus, although the MW is unusual, it is consistent with the overall population of MW-mass disk galaxies. The direct MW analogs assemble most of their mass early, $\gtrsim 10$ Gyr ago, and are not affected by destructive mergers after that. In addition, these galaxies form their disks during the early enrichment stage when the interstellar medium metallicity increases rapidly, with only $\sim$25% of early-forming disks being as metal-poor as the MW was at the onset of disk formation, [Fe/H] $\approx -1.0$. In contrast, most MW-mass galaxies either form disks from already enriched material or experience late destructive mergers that reset the signatures of galactic disk formation to later times and higher metallicities. Finally, we also show that earlier disk formation leads to more dominant rotationally supported stellar disks at redshift zero.
Announcing the release v2 of the MORX (Millions of Optical-Radio/X-ray Associations) catalogue which presents probable (40%-100% likelihood) radio/X-ray associations, including double radio lobes, to optical objects over the whole sky. Detections from all the largest radio/X-ray surveys to June 2023 are evaluated, those surveys being VLASS, LoTSS, RACS, FIRST, NVSS, and SUMSS radio surveys, and Chandra, XMM-Newton, Swift, and ROSAT X-ray surveys. The totals are 3,115,575 optical objects of all classifications (or unclassified) so associated. The MORX v2 catalogue is available on multiple sites.
This study focuses on Pristine$\_180956.78$$-$$294759.8$ (hereafter P180956, $[Fe/H] =-1.95\pm0.02$), a star selected from the Pristine Inner Galaxy Survey (PIGS), and followed-up with the recently commissioned Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South telescope. The GHOST spectrograph's high efficiency in the blue spectral region ($3700-4800$~\AA) enables the detection of elemental tracers of early supernovae (\eg Al, Mn, Sr, Eu). The star exhibits chemical signatures resembling those found in ultra-faint dwarf systems, characterised by very low abundances of neutron-capture elements (Sr, Ba, Eu), which are uncommon among stars in the Milky Way halo. Our analysis suggests that P180956 bears the chemical imprints of a small number (2 or 4) of low-mass hypernovae ($\sim10-15 M_{\odot}$), which are needed to mostly reproduce the abundance pattern of the light-elements (\eg [Si, Ti/Mg, Ca] $\sim0.6$), and one fast-rotating intermediate-mass supernova ($\sim300\kms$, $\sim80-120 M_{\odot}$), which is the main channel contributing to the high [Sr/Ba] ($\sim +1.2$). The small pericentric ($\sim0.7$ kpc) and apocentric ($\sim13$ kpc) distances and its orbit confined to the plane ($\lesssim 2$ kpc), indicate that this star was likely accreted during the early Galactic assembly phase. Its chemo-dynamical properties suggest that P180956 formed in a system similar to an ultra-faint dwarf galaxy accreted either alone, as one of the low-mass building blocks of the proto-Galaxy, or as a satellite of Gaia-Sausage-Enceladus. The combination of Gemini's large aperture with GHOST's high efficiency and broad spectral coverage makes this new spectrograph one of the leading instruments for near-field cosmology investigations.
Radio wavelengths offer a unique possibility to trace the total star-formation rate (SFR) in galaxies, both obscured and unobscured. To probe the dust-unbiased star-formation history, an accurate measurement of the radio luminosity function (LF) for star-forming galaxies (SFGs) is crucial. We make use of an SFG sample (5900 sources) from the Very Large Array (VLA) COSMOS 3 GHz data to perform a new modeling of the radio LF. By integrating the analytical LF, we aim to calculate the history of the cosmic SFR density (SFRD) from $z\sim5$ onwards. For the first time, we use both models of the pure luminosity evolution (PLE) and joint luminosity+density evolution (LADE) to fit the LFs directly to the radio data using a full maximum-likelihood analysis, considering the sample completeness correction. We also incorporate updated observations of local radio LFs and radio source counts into the fitting process to obtain additional constraints. We find that the PLE model cannot be used to describe the evolution of the radio LF at high redshift ($z>2$). By construct, our LADE models can successfully fit a large amount of data on radio LFs and source counts of SFGs from recent observations. We therefore conclude that density evolution is genuinely indispensable in modeling the evolution of SFG radio LFs. Our SFRD curve shows a good fit to the SFRD points derived by previous radio estimates. In view of the fact that our radio LFs are not biased, as opposed those of previous studies performed by fitting the $1/V_{\rm max}$ LF points, our SFRD results should be an improvement on these previous estimates. Below $z\sim1.5$, our SFRD matches a published multiwavelength compilation, while our SFRD turns over at a slightly higher redshift ($2<z<2.5$) and falls more rapidly out to high redshift.
We investigate a mechanism to form and keep a planar spatial distribution of satellite galaxies in the Milky Way (MW), which is called the satellite plane. It has been pointed out that the {\Lambda}CDM cosmological model hardly explains the existence of such a satellite plane, so it is regarded as one of the serious problems in the current cosmology. We here focus on a rotation of the gravitational potential of a host galaxy, i.e., so-called a figure rotation, following the previous suggestion that this effect can induce the tilt of a so-called tube orbit. Our calculation shows that a figure rotation of a triaxial potential forms a stable orbital plane perpendicular to the rotational axis of the potential. Thus, it is suggested that the MW's dark halo is rotating with its axis being around the normal line of the satellite plane. Additionally, we find that a small velocity dispersion of satellites is required to keep the flatness of the planar structure, namely the standard derivation of their velocities perpendicular to the satellite plane needs smaller than their mean rotational velocity on the plane. Although not all the MW's satellites satisfy this condition, some fraction of them called member satellites, which are prominently on the plane, satisfy it. We suggest that this picture explaining the observed satellite plane can be achieved by the filamentary accretion of dark matter associated with the formation of the MW and a group infall of member satellites along this cosmic filament.
Henri Camichel was an astronomer at Pic du Midi Observatory, where he contributed to the study of planets of the solar system and their satellites with Audouin Dollfus and his team. In 1961, with Charles Boyer, he found that the upper atmosphere of Venus had a counter-clockwise rotation of four days, which was later confirmed by space probes, as were the team's accurate measurements of the diameters of planets. He was also an instrumentalist, and contributed to the maintenance and development of the telescopes, notably the 2-meter telescope and focal instruments at Pic du Midi Observatory.
The initial distribution of rotational velocities of stars is still poorly known, and how the stellar spin evolves from birth to the various end points of stellar evolution is an actively debated topic. Binary interactions are often invoked to explain the existence of extremely fast-rotating stars ($v\sin\,i$ $\gtrsim$ 200 $km\,s^{-1}$). The primary mechanisms through which binaries can spin up stars are tidal interactions, mass transfer, and possibly mergers. To evaluate these scenarios, we investigated in detail the evolution of three known fast-rotating stars in short-period spectroscopic and eclipsing binaries, namely HD 25631, HD 191495, and HD 46485, with primaries of masses of 7, 15, and 24 $M_{\odot}$, respectively, with companions of $\sim1\,M_\odot$ and orbital periods of less than 7 days. These systems belong to a recently identified class of binaries with extreme mass ratios, whose evolutionary origin is still poorly understood. We evaluated in detail three scenarios that could explain the fast rotation observed in these binaries: it could be primordial, a product of mass transfer, or the result of a merger within an originally triple system. We computed grids of single and binary MESA models varying tidal forces and initial binary architectures to investigate the evolution and reproduce observational properties of these systems. We find that, because of the extreme mass-ratio between binary components, tides have a limited impact, regardless of the prescription used, and that the observed short orbital periods are at odds with post-mass-transfer scenarios. The most likely scenario to form such young, rapidly rotating, and short-period binaries is primordial rotation, implying that the observed binaries are pre-interaction ones. These binaries show that the initial spin distribution of massive stars can have a wide range of rotational velocities.
The memory effect in gravitational waves is a direct prediction of general relativity. The presence of the memory effect in gravitational wave signals not only serves as a test for general relativity but also establishes connections between soft theorem, and asymptotic symmetries, serving as a bridge for exploring fundamental physics. Furthermore, with the ongoing progress in space-based gravitational wave detection projects, the gravitational wave memory effect generated by the merger of massive binary black hole binaries is becoming increasingly significant and cannot be ignored. In this work, we perform the full Bayesian analysis of the gravitational wave memory effect with TianQin. The results indicate that the memory effect has a certain impact on parameter estimation but does not deviate beyond the 1$\sigma$ range. Additionally, the Bayes factor analysis suggests that when the signal-to-noise ratio of the memory effect in TianQin is approximately 2.36, the $\text{log}_{10}$ Bayes factor reaches 8. This result is consistent with the findings obtained from a previous mismatch threshold.
With their high angular resolutions of 30-100 mas, large fields of view, and complex optical systems, imagers on next-generation optical/near-infrared space observatories, such as the Near-Infrared Camera (NIRCam) on the James Webb Space Telescope (JWST), present both new opportunities for science and also new challenges for empirical point spread function (PSF) characterization. In this context, we introduce ShOpt, a new PSF fitting tool developed in Julia and designed to bridge the advanced features of PIFF (PSFs in the Full Field of View) with the computational efficiency of PSFEx (PSF Extractor). Along with ShOpt, we propose a suite of non-parametric statistics suitable for evaluating PSF fit quality in space-based imaging. Our study benchmarks ShOpt against the established PSF fitters PSFEx and PIFF using real and simulated COSMOS-Web Survey imaging. We assess their respective PSF model fidelity with our proposed diagnostic statistics and investigate their computational efficiencies, focusing on their processing speed relative to the complexity and size of the PSF models. Despite being in active development, we find that ShOpt can already achieve PSF model fidelity comparable to PSFEx and PIFF while maintaining competitive processing speeds, constructing PSF models for large NIRCam mosaics within minutes.
In the context of the ATHENA X-IFU Cryogenic AntiCoincidence Detector (CryoAC) development, we have studied the thermalization properties of a 2mm x 2mm SQUID chip. The chip is glued on a front-end PCB and operated on the cold stage of a dilution refrigerator (TBASE < 20 mK). We performed thermal conductance measurements by using different materials to glue the SQUID chip on the PCB. These have been repeated in subsequent cryostat runs, to highlight degradation effects due to thermal cycles. Here, we present the results obtained by glues and greases widely used in cryogenic environments, i.e. GE 7031 Varnish Glue, Apiezon N Grease and Rubber Cement.
The investigation of cosmic rays holds significant importance in the realm of particle physics, enabling us to expand our understanding beyond atomic confines. However, the origin and characteristics of ultra-high-energy cosmic rays remain elusive, making them a crucial topic of exploration in the field of astroparticle physics. Currently, our examination of these cosmic rays relies on studying the extensive air showers (EAS) generated as they interact with atmospheric nuclei during their passage through Earth's atmosphere. Accurate comprehension of cosmic ray composition is vital in determining their source. Notably, the muon content of EAS and the atmospheric depth of the shower maximum serve as the most significant indicators of primary mass composition. In this study, we present two novel methods for reconstructing particle densities based on muon counts obtained from underground muon detectors (UMDs) at varying distances to the shower axis. Our methods were analyzed using Monte Carlo air shower simulations. To demonstrate these techniques, we utilized the muon content measurements from the UMD of the Pierre Auger cosmic ray Observatory, an array of detectors dedicated to measuring extensive air showers. Our newly developed reconstruction methods, employed with two distinct UMD data acquisition modes, showcased minimal bias and standard deviation. Furthermore, we conducted a comparative analysis of our approaches against previously established methodologies documented in existing literature.
The main factors that influence the success of observations in the infrared range (central wavelengths of the photometric bands at 3.75 and 4.8~$\mu$m) on the multipurpose optical telescope are considered. Estimates of the sky background brightness are obtained for the Caucasus Mountain Observatory (CMO) of Moscow State University: $1.3\cdot10^6$~photons/(s pixel) in the 3.75~$\mu$m band and $3.4\cdot10^6$~photons/(s pixel) in the 4.8~$\mu$m; and the instrumental background for the 2.5-m CMO telescope at $0^\circ$C: $3.2\cdot10^6$~photons/(s pixel) in the 3.75~$\mu$m band and $4.3\cdot10^6$~photons/(s pixel) in the 4.8~$\mu$m band. It is shown that at this background signal level with the currently available commercial cameras in the $3-5$~$\mu$m spectral range, the telescope-camera coupling capabilities for observing faint objects will still be limited by the thermal background. For different observational conditions, estimates of the limiting magnitudes of objects available for observations in the 3.75 and 4.8~$\mu$m ranges are obtained. For average observation conditions (instrument temperature of $0^\circ$C and stellar image size of 1 arcsec), the limit is $\sim10.6^m$ and $\sim8.4^m$, respectively.
As the OSIRIS-REx spacecraft descended toward the asteroid Bennu to collect a sample from the surface in the touch-and-go (TAG) procedure, many of the instruments were actively collecting observation data. We applied the process of photogrammetric control to accurately determine the position and attitude of 190 OCAMS MapCam and SamCam descent images at the time of exposure. The average image pixel resolution is 10cm (median is 7cm). The images were controlled to ground using simulated images generated from high resolution (5cm, 44cm and 88cm ground sample distance) shape models of Bennu. After least-squares adjustment, the root mean square (rms) of all image measurement residuals was 0.16 pixels. These results were applied to 581 OTES observations by interpolation over the updated ephemeris of the OCAMS MapCam and SamCam instruments using frame transformations from OCAMS to the OTES frame. Then, the surface intercept of the OTES field of view was recomputed by ray tracing the adjusted boresight look direction onto the 44cm shape model. The average of the adjusted OTES boresight surface intercepts differed from the a priori locations on the 88cm shape model by ~37cm with an uncertainty less than 5cm.
This paper documents the results from the highly successful Lunar flashlight Optical Navigation Experiment with a Star tracker (LONEStar). Launched in December 2022, Lunar Flashlight (LF) was a NASA-funded technology demonstration mission. After a propulsion system anomaly prevented capture in lunar orbit, LF was ejected from the Earth-Moon system and into heliocentric space. NASA subsequently transferred ownership of LF to Georgia Tech to conduct an unfunded extended mission to demonstrate further advanced technology objectives, including LONEStar. From August-December 2023, the LONEStar team performed on-orbit calibration of the optical instrument and a number of different OPNAV experiments. This campaign included the processing of nearly 400 images of star fields, Earth and Moon, and four other planets (Mercury, Mars, Jupiter, and Saturn). LONEStar provided the first on-orbit demonstrations of heliocentric navigation using only optical observations of planets. Of special note is the successful in-flight demonstration of (1) instantaneous triangulation with simultaneous sightings of two planets with the LOST algorithm and (2) dynamic triangulation with sequential sightings of multiple planets.
The automatic classification of X-ray detections is a necessary step in extracting astrophysical information from compiled catalogs of astrophysical sources. Classification is useful for the study of individual objects, statistics for population studies, as well as for anomaly detection, i.e., the identification of new unexplored phenomena, including transients and spectrally extreme sources. Despite the importance of this task, classification remains challenging in X-ray astronomy due to the lack of optical counterparts and representative training sets. We develop an alternative methodology that employs an unsupervised machine learning approach to provide probabilistic classes to Chandra Source Catalog sources with a limited number of labeled sources, and without ancillary information from optical and infrared catalogs. We provide a catalog of probabilistic classes for 8,756 sources, comprising a total of 14,507 detections, and demonstrate the success of the method at identifying emission from young stellar objects, as well as distinguishing between small-scale and large-scale compact accretors with a significant level of confidence. We investigate the consistency between the distribution of features among classified objects and well-established astrophysical hypotheses such as the unified AGN model. This provides interpretability to the probabilistic classifier. Code and tables are available publicly through GitHub. We provide a web playground for readers to explore our final classification at https://umlcaxs-playground.streamlit.app.
Reproduction experiments of radial pyroxene (RP) chondrules were carried out using an Ar-$\mathrm{H_2}$ or Ar gas-jet levitation system in a reducing atmosphere in order to simulate chondrule formation in the protoplanetary disk. The experiments reproduced RP-chondrule textures, consisting of sets of thin pyroxene crystals and mesostasis glass between crystals. However, iron partition coefficients between pyroxene and glassy mesostasis ($\rm{D_{Fe}}$ = Fe mol$\rm{\%_{pyroxene}}$ / Fe mol$\rm{\%_{mesostasis}}$) in natural RP chondrules were much higher than that in experimentally reproduced RP chondrules. The high $\rm{D_{Fe}}$ in natural RP chondrules suggest that iron was removed from the mesostasis melt at high temperatures after the growth of pyroxene crystals. We found that many small iron-metal inclusions had formed in the mesostasis glass, indicating that FeO in the high-temperature melt of mesostasis was reduced to metallic iron, and iron in the mesostasis diffused into the newly formed metal inclusions. The formation of the iron-metal inclusions in the mesostasis was reproduced by our experiments in a reducing atmosphere, confirming that $\rm{D_{Fe}}$ in natural RP chondrules increased after the growth of RP crystals. Therefore, the $\rm{D_{Fe}}$ of RP chondrules can be an indicator to constrain cooling rates and redox states during chondrule formation.
Zeeman-Doppler imaging (ZDI) is used to reconstruct the surface magnetic field of late-type stars from high resolution spectropolarimetric observations. The results are usually described in terms of characteristics of the field topology, i.e. poloidality vs. toroidality and axi-symmetry vs. non-axisymmetry in addition to the field strength. We want to test how well these characteristics are preserved when applying the ZDI method on simulated data, i.e. how accurately the field topology is preserved and to what extent stellar parameters influence the reconstruction. We use published magnetic field data from direct numerical MHD simulations. These have variable rotation rates, and hence represent different levels of activity, of an otherwise Sun-like setup. Our ZDI reconstruction is based on spherical harmonics expansion. By comparing the original values to those of the reconstructed images, we study the ability to reconstruct the surface magnetic field in terms of various characteristics of the field. The main large-scale features are reasonably well recovered, but the strength of the recovered magnetic field is just a fraction of the original input. The quality of the reconstruction shows clear correlations with the data quality. Furthermore, there are some spurious dependencies between stellar parameters and the characteristics of the field. Our study uncovers some limits of ZDI. Firstly, the recovered field strength will generally be lower than the "real" value as smaller structures with opposite polarities will be blurred in the inversion. Secondly, the axisymmetry is overestimated. The poloidality vs. toroidality is better recovered. The reconstruction works better for a stronger field and faster rotation velocity. Still, the ZDI method works surprisingly well even for a weaker field and slow rotation, provided the data has a high signal-to-noise and good rotation phase coverage.
Undergraduate physics and astronomy students are expected to engage with scientific literature as they begin their research careers, but reading comprehension skills are rarely explicitly taught in major courses. We seek to determine the efficacy of lesson plans designed to improve undergraduate astronomy (or related) majors' perceived ability to engage with research literature by using accessible summaries of current research written by experts in the field. During the 2022-2023 academic year, twelve faculty members incorporated lesson plans using accessible summaries from Astrobites into their undergraduate astronomy major courses, surveyed their students before and after the activities, and participated in follow-up interviews with our research team. Quantitative and qualitative survey data clearly show that students' perceptions of their abilities with jargon, identifying main takeaways of a paper, conceptual understanding of physics and astronomy, and communicating scientific results all improved with use of the tested lesson plans. Additionally, students show evidence of increased confidence of their abilities within astronomy after exposure to these lessons, and instructors valued a ready-to-use resource to incorporate reading comprehension in their pedagogy. This case study with Astrobites-based lesson plans suggests that incorporating current research in the undergraduate classroom through accessible literature summaries may increase students' confidence and ability to engage with research literature, as well as their preparation for participation in research and applied careers.
This paper presents GPFC, a novel Graphics Processing Unit (GPU) Phase Folding and Convolutional Neural Network (CNN) system to detect exoplanets using the transit method. We devise a fast folding algorithm parallelized on a GPU to amplify low signal-to-noise ratio transit signals, allowing a search at high precision and speed. A CNN trained on two million synthetic light curves reports a score indicating the likelihood of a planetary signal at each period. While the GPFC method has broad applicability across period ranges, this research specifically focuses on detecting ultra-short-period planets with orbital periods less than one day. GPFC improves on speed by three orders of magnitude over the predominant Box-fitting Least Squares (BLS) method. Our simulation results show GPFC achieves $97%$ training accuracy, higher true positive rate at the same false positive rate of detection, and higher precision at the same recall rate when compared to BLS. GPFC recovers $100\%$ of known ultra-short-period planets in $\textit{Kepler}$ light curves from a blind search. These results highlight the promise of GPFC as an alternative approach to the traditional BLS algorithm for finding new transiting exoplanets in data taken with $\textit{Kepler}$ and other space transit missions such as K2, TESS and future PLATO and Earth 2.0.
This paper investigates the observational signatures of hot spots orbiting scalarized Reissner-Nordstr\"om black holes, which have been reported to possess multiple photon spheres. In contrast to the single-photon sphere case, hot spots orbiting black holes with two photon spheres produce additional image tracks in time integrated images capturing a complete orbit of hot spots. Notably, these newly observed patterns manifest as a distinct second-highest peak in temporal magnitudes when observed at low inclination angles. These findings offer promising observational probes for distinguishing black holes with multiple photon spheres from their single-photon sphere counterparts.
In this comment, we showed that the Dirac equation in the screw dislocation space-time also carries a term that represents the torsion of such topological defect, given by $K_\mu$. Therefore, the Dirac equation worked by Wang et al. is incomplete since such a term was ignored in your equation (what cannot happen). In other words, it is only possible to work with the Dirac equation in the form presented by Wang et al. if the space-time is torsion-free, which is obviously not the case.
Here the Weyl curvature hypothesis is examined using the gravitational entropy (GE). We have considered the family of C-metric accelerating black holes and evaluated their corresponding gravitational entropy. Then we studied the GE in some isotropic and anisotropic cosmologies utilizing the definition proposed by Clifton, Ellis, and Tavakol, where the Bel-Robinson tensor is used to determine the energy-momentum tensor of the free gravitational field. We checked whether, in the vicinity of the initial cosmic singularity, the ratio of the energy density of free gravity to that of matter density goes to zero or not. We showed that whenever this is true, the gravitational entropy increases monotonically with the structure formation of the universe and discussed the conditions of validity for the Weyl curvature hypothesis. Subsequently, the next part of the thesis deals with the validity of two different proposals of gravitational entropy (GE) in traversable wormhole systems. We found that the GE proposals do provide us with a consistent measure of GE in several wormhole solutions. In the later portion of the thesis, we examined the validity of the generalized second law of thermodynamics (GSLT) in an expanding FRW universe filled with different variants of the Chaplygin gas. Lastly, we studied the evolution of the FRW universe in the presence of variable modified Chaplygin gas and obtained its temperature and other parameters as a function of the redshift. Finally, the thesis is concluded.
Inspired by the method of smoothed asymptotics developed by Terence Tao, we introduce a new ultra-violet regularisation scheme for loop integrals in quantum field theory which we call $\eta$ regularisation. This allows us to reveal a surprising connection between the elimination of divergences in divergent series of powers and the preservation of gauge invariance in the regularisation of loop integrals in quantum field theory. In particular, we note that a method for regularising the series of natural numbers so that it converges to minus one twelfth inspires a regularisation scheme for non-abelian gauge theories coupled to Dirac fermions that preserves the Ward identity for the vacuum polarisation tensor. We also comment on a possible connection to Schwinger proper time integrals.
We investigate the Noether symmetries of the Klein--Gordon Lagrangian for Bianchi I spacetime. This is accomplished using a set of new Noether symmetry relations for the Klein--Gordon Lagrangian of Bianchi I spacetime, which reduces to the wave equation in a special case. A detailed Noether symmetry analysis of the Klein--Gordon and the wave equations for Bianchi I spacetime is presented, and the corresponding conservation laws are derived.
We present a toymetric of spacetime travel from topological change. A bubble-like baby universe is detached and re-attached fromour universe. Dependingon where the bubble is re-attached, matter may travel superluminally or backwards-in-time through the bubble. Quasiregular singularities are formed at the detachment and re-attachment spacetime points. The spacetime is traversable and not covered by any horizons. Exotic matters violating energy conditions are required to realize such spacetimes.
Ever since Penrose and Simpson contradicted Novikov's prediction that an infalling passenger would emerge into an asymptotically flat universe, there have been a continued interest in predicting the nature of singularity at the Cauchy horizon of a Reissner-Nordstrom blackhole. This prediction was first confirmed by Poisson and Israel using cross-stream of massless particles, suggesting the phenomenon of mass inflation. Ori however obtained a weaker singularity using a null shell of radiation. In this work, we consider a massive scalar field coupled to the Reissner-Nordstrom geometry and analyze the nature of singularity at the Cauchy horizon. To study the asymptotic behavior of the mass function and the scalar field near the Cauchy horizon, we perturbatively solve the coupled dynamical equations emplyoing the Adomian decomposition method. Our analysis shows that the mass function exhibits a very rapid and unbounded double-exponential growth, called herein mass superinflation, which is enormously stronger than previously obtained singularities. The scalar field is also found to undergo a very strong blueshift near the Cauchy horizon.
The Weak Cosmic Censorship Conjecture, since its proposal, has always been a controversial hypothesis, but its significance in astrophysics is undeniable. For a regular black hole, its center does not contain a singularity, and the destruction of the horizon of such black holes is not protected by the Weak Cosmic Censorship Conjecture. Therefore, we employ Gedanken experiments to study the hairy Kerr black holes, which are promising candidates to serve as "simulators" of astrophysical black holes. By investigating these black holes through testing particles and scalar fields carrying large angular momentum, we explore whether these black holes can achieve overspinning. Our results suggest that the overspinning behavior of these hairy Kerr black holes in extreme or near-extreme conditions strongly depends on the hairy parameters (${\alpha, l_0}$). This not only potentially offers us an opportunity to explore the interior structure of black holes, but may also provide clues for constraining the hairy parameters. This phenomenon might reveal the connection between the no-hair theorem of black holes and the weak cosmic censorship conjecture, bringing new perspectives to our understanding of these theories.
Since the proposal of the Weak Cosmic Censorship Conjecture, numerous studies have emerged. In this paper, we investigate by injecting a test particle and a scalar field into a Kerr-like black hole immersed in a dark matter halo. We consider both first-order and higher-order cases and find that Kerr-like black holes immersed in a dark matter halo do not violate the Weak Cosmic Censorship Conjecture. However, when a test particle is dropped in, there exists a possibility in the near-extremal condition where the event horizon of the black hole can be destroyed. Overall, our analysis suggests that the presence of a dark matter halo hinders the super-spinning of black holes, implying that cold dark matter seems to play a protective role. Without considering cold dark matter, our conclusions are consistent with previous research.
A detailed study of ray tracing in the space-time generated by a disk of counter-rotating dust is presented. The space-time is given in explicit form in terms of hyperelliptic theta functions. The numerical approach to ray tracing is set up for general stationary axisymmetric space-times and tested at the well-studied example of the Kerr solution. Similar features as in the case of a rotating black hole, are explored in the case of a dust disk. The effect of the central redshift varying between a Newtonian disk and the ultrarelativistic disk, where the exterior of the disk can be interpreted as the extreme Kerr solution, and the transition from a single component disk to a static disk is explored. Frame dragging, as well as photon spheres, are discussed.
We explore the possibility of a consistent cosmology based on the gauge-fixing independent running of the gravitational and cosmological constants ($G$ and $\Lambda$) in the framework of effective quantum gravity. In particular, their running in this framework was found to satisfy $G \propto \Lambda^4$. In the cosmological setting, the covariance of the theory provides energy conservation relations, which are impossible to satisfy with the unique scale parameter. However, by introducing the second sub-dominant scale corresponding to the higher-loop corrections and higher-derivative terms, one can close the system of equations for the running of parameters and arrive at the consistent cosmological solutions. This approach yields a change in the cosmological expansion history that affects the ratio of the Hubble parameter today to the Hubble parameter at high redshift.
The primary constraints for general teleparallel quadratic gravity is presented. This gives a basic classification of these theories from the perspective of the full nonlinear theory and is the first step towards a full-fledged Hamiltonian analysis. The results are consistent with the limit of metric and symmetric teleparallel quadratic gravity. In the latter case we also present novel results, since symmetric teleparallel theories have only been partially studied so far. Apart from the general results, we also present the special cases of teleparallel theories classically equivalent to general relativity. They differ by a boundary term from the formulation of Einstein and Hilbert and this affects the constraint algebra. This implies that the symmetries of general relativity are realized in a more intricate way and it becomes evident that the primary constraints involve a mix of torsion and non-metricity. In this context, a more detailed understanding will provide insights for energy and entropy in gravity, quantum gravity and numerical relativity of this alternative formulation of general relativity. The primary constraints are presented both in the standard formulation and in irreducible parts of torsion and non-metricity. The special role of axial torsion and its connection to the one-parameter of viable new general relativity is confirmed. Furthermore, we find that one of the irreducible parts of non-metricity affects the primary constraint for shift but not lapse.
The scalar fields, $U(1)$ gauge vector fields, and Kalb-Ramond fields are the $0$-form, 1-form, and 2-form fields, respectively. In four-dimensional space-time, free $q$-form fields are equivalent to scalar or vector fields by a duality, however, in higher-dimensional space-time, $q-$form fields correspond to new types of particles. In this paper, with considering a coupling mechanism between the kinetic term of the $q-$form fields and the background spacetime, we investigate the localization of Kaluza-Klein modes for the $q-$form fields on a $D-$dimensional Randall-Sundrum-like brane model. We demonstrate that the zero mode can be localized on the brane, and the massive Kaluza-Klein modes could be localized or quasi-localized on the brane when with certain value of parameters. Then, we present the localization of the scalar fields, $U(1)$ gauge vector fields, and 2-form Kalb-Ramond fields within a five-dimensional bulk spacetime. For a massless scalar field, an interesting characteristic emerges: When the parameter $t_2$ is negative, the zero mode is localized on both sides of the brane, whereas the massive Kaluza-Klein modes can be quasi-localized at the center of the brane.
This paper defines the photon surface conditions using Cartan scalars within an invariant spin frame, offering a comprehensive description of the local spacetime geometry. By employing this approach, we gain novel insights into the geometry and dynamics of photon surfaces, independent of the global spacetime structure. We first discuss the photon surface conditions in a Petrov type-D spacetime manifold, and then we simplify those conditions assuming the existence of spherical symmetry. Finally, employing the simplified, spherically symmetric photon surface conditions, we explore the dynamics of photon surfaces in static, collapsing Lemaitre-Tolman-Bondi (LTB) spacetimes, and Vaidya spacetimes. Notably, we show that photon surfaces can emerge from the central singularity during the collapse of an inhomogeneous dust cloud modeled by a LTB spacetime. This underscores the significance of our findings in comprehending the potential observational implications of the physics near the ultra-high gravity region.
This paper explores the evolution of the over-dense region of dark matter in the presence of a non-minimally coupled scalar field which is used to model quintessence and phantom-like dark energy. We focus on algebraic coupling, where the interaction Lagrangian is independent of the derivatives of the scalar field. To make our model more relativistic, like the minimal coupling scenario we studied earlier, we consider a spacetime structure that is internally closed Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime and externally the generalized Vaidya spacetime. This structure allows non-zero matter flux at the boundary of the over-dense region. Our investigation reveals that an increment of the coupling strength causes dark energy to cluster with dark matter at a certain cosmological scale where the influence of dark energy cannot be ignored. This phenomenon arises from the specific nature of the non-minimal coupling considered in this paper. While the evolution of matter's energy density remains unchanged, the scalar field's Klein-Gordon equation is modified, causing dark energy to deviate from its homogeneous state and cluster with dark matter. Similar to minimal coupling scenarios, closed spherical regions do not collapse within certain parameter ranges, exhibiting eternal expansion within the spatially flat FLRW spacetime acting as voids with decreasing matter density. The study extends our understanding of the cosmological scenarios where the virialization of the over-dense regions of dark matter is influenced by the non-minimally coupled dark energy.
A reformulation of general relativity inspired by the Belinski-Khalatnikov-Lifshitz conjecture had been introduced by Ashtekar, Henderson and Sloan which is based on variables closely related to the basic variables of loop quantum gravity, thereby providing a way of classically analyzing singularities that may be carried over to the quantum theory. It is reasonable to expect that these variables are regular at generic spacelike singularities. This has been shown on various examples -- particularly, cosmological spacetimes. In this study we extend this analysis to the singularities of gravitational wave collision spacetimes, which are the result of the mutual focusing of the two waves. We focus on two specific examples and explicitly confirm that the said variables are regular at the singularity and can be smoothly continued beyond it.
We investigate the genuine multipartite entanglement, global entanglement, and quantum coherence among different configurations of a penta-partite system involving particles inside and outside the event horizon of a Schwarzschild black hole. We consider and analyze different scenarios based on how many particles are accessible. In each scenario, we evaluate first-order coherence, concurrence fill, and global concurrence under varying Hawking temperature and Dirac particle mode frequency. For the fully accessible scenario with all particles outside the event horizon, the measures exhibit non-monotonic behavior with a discernible trade-off. In the partially accessible scenarios with one particle inside the event horizon, monotonic variations and clear trade-offs are observed. Finally, in the scenario when two particles are inside the event horizon, concurrence fill becomes complex, attributed to the violation of the entanglement polygon inequality in curved space-time. This result reveals intricate relationships between entanglement and coherence around the event horizon of Schwarzchild black holes. Our findings suggest reevaluating entanglement polygon inequalities and concurrence fill for applicability in flat and curved space-times. These insights contribute to our understanding of quantum information dynamics and gravitational impacts on entanglement in extreme environments.
We propose the method for construction of $F(R,\xi)$ gravity model, unifying inflation and primordial black hole formation. The proposed models are based on the Starobinsky $R+R^2$ inflationary model, so, the function $F(R,\xi)$ is a quadratic polynomial of the Ricci scalar $R$. We show that the potential of the corresponding two-field chiral cosmological model in the Einstein frame can be always found in terms of the elementary functions. The special choice of the function $F(R,\xi)$ allows us to get such a generalization of the hybrid inflation that can describe both inflation, and the primordial black hole formation.
In this paper, we study asymptotic symmetries and algebraically special exact solutions in the Newman-Penrose formalism. Removing the hypersurface orthogonal condition in the well studied Newman-Unti gauge, we obtain a generic asymptotic solution space which includes all possible origins of propagating degree of freedom. The asymptotic symmetry of the generalized system extends the Weyl-BMS symmetry by two independent local Lorentz transformations with non-trivial boundary charges, which reveals new boundary degrees of freedom. The generalized Newman-Unti gauge includes algebraically special condition in its most convenient form. Remarkably, the generic solutions satisfying the algebraically special condition truncate in the inverse power of radial expansions and the non-radial Newman-Penrose equations are explicitly solved at any order. Hence, we provide the most general algebraically special solution space and the derivation is self-contained in the Newman-Penrose formalism. The asymptotic symmetry with respect to the algebraically special condition is the standard Weyl-BMS symmetry and the symmetry parameters consist only the integration constant order. We present the Kerr solution and Taub-NUT solution in the generalized Newman-Unti gauge in a simple form.
One of the most important sources for the space-borne gravitational wave detectors such as TianQin and LISA, is the merger of massivie black hole binaries. Using the inspiral signals, we can probe the properties of the massive black holes, such as the spin-induced multipole moments. By verifying the relation among the mass, spin and quadrupole moment, the no-hair theoreom can be tested. In this work, we analysed the capability on probing the spin-induced quadrupole moment with the inspiral signal of massive black hole binaries using space-borne gravitational wave detectors. Using the Fisher information matrix, we find that the deviation of quadrupole moment can be constrained to the level of $10^{-1}$, and the events with higher mass-ratio will give a better constraint. We also find that the late inspiral part will dominate the result of parameter estimation. The result of Bayesian analysis shows that the capability will be improved by a few times due to the consideration of higher modes. We also calculate the Bayes factor, and the results indicate that the model of black hole and Boson star can be distinguished undoubtedly.
In this work, we extend previous results, demonstrating how complexity in an open quantum system can identify decoherence between two fields, even in the presence of an accelerating background. Using the curved-space Caldeira-Leggett two-field model in de Sitter as our toy model, we discover a distinctive feature in the growth of complexity of purification, providing an alternative diagnostic for studying decoherence when the adiabatic perturbation is coupled to a heavy field. This paper initiates a new pathway to explore the features of quantum complexity in an accelerating background, thereby expanding our understanding of the evolution of primordial cosmological perturbations in the early universe.
The aim of this work is to use the notions of Riemann's geometry introduced in Part I, to analyze the foundations of Einstein's theory of general relativity.
The central question in this article is how information does leak out from black holes. Relying on algebraic arguments and the concept of superselection sectors, we propose the existence of certain operators whose correlations extend across the black hole atmosphere and range into the interior. Contained in the full algebra, these black hole intertwiners will not belong to the subalgebra describing semiclassical bulk physics. We study this proposal in the context of operator reconstructions for code spaces containing a large number of microstates. As long as the atmosphere is excluded from a particular subsystem, the global state seen under the action of the associated algebra is maximally mixed and therefore described by a single classical background. Once the relevant correlations are encoded, i.e. if the algebra is sufficiently enlarged, perfect state distinguishability becomes possible. We arrive at this by computing the von Neumann entropy which may explain the result obtained by applying the quantum extremal surface prescription to the mixed state. We then examine these insights in the context of black hole evaporation and argue that information is transferred to the radiation via black hole intertwiners. We derive the Page curve. The mechanism above suggests that black hole information is topologically protected. An infalling observer would experience no drama. This may resolve the unitarity problem without running into any firewall or state puzzle, the latter being evident in generalized entropy computations. We also examine the question of how certain wormhole topologies may be understood given these findings. We argue that their occurrence in gravity replica computations may be related to the maximal correlation between radiation and atmosphere surrounding the old black hole. This may suggest a connection between topology change and near horizon quantum gravitational effects.
It is usually stated that the information storing region associated with the Bekenstein-Hawking entropy is enclosed by a sphere of diameter equal twice the Schwarzschild radius. We point out that this cannot apply to a quantum black hole. The deviation is particularly revealed when the latter is maximally correlated with its Hawking radiation. Specifically, we demonstrate that the size of the entropy sphere associated with the underlying microstructure has to be necessarily broadened when the fine grained radiation entropy becomes maximal. Such an enlargement is understood to be the consequence of unitarization effects in quantum gravity and aligns with recent findings in holography arguing that purification happens via semiclassically invisible quantum correlations extending across the black hole atmosphere. In the present work, we consider an evaporating black hole in asymptotically flat spacetime. We assume that the standard thermodynamical description is valid so long the black hole viewed from the outside is sufficiently large, radiation escaping into the future null infinity can be described on a smooth spacetime background, and the von Neumann entropy of Hawking radiation evolves unitarily. We briefly comment on the black hole singularity.
Cylindrically symmetric vacuum spacetimes are of immense interest in theoretical physics due to its connection to cosmic strings hypothesized in quantum field theory. In this article, we explore the properties of such spacetime and provide the complete solution to the time- and light-like geodesics in it using Hamilton-Jacobi formalism. In addition, we compare several properties and massive particle trajectories of relativistic cylindrically symmetric vacuum spacetimes to its non-relativistic, Newtonian gravitational counterparts.
According to the holographic principle, the information content assigned to a gravitational region is processed by its lower dimensional boundary. As an example setup compatible with this principle, the AdS/CFT correspondence relies on the existence of D-branes in superstring theory. Black hole complementarity is inevitably linked to holography and states that information associated with the collapsed pure state is reflected in the near horizon region. Yet, if this is so, it is indispensable to understand the mechanism that makes black holes viewed from the outside evolve unitarily. We here argue that the information preserving quantum atmosphere of the black hole emerges from hidden variables on its horizon which would necessitate going beyond a probabilistic description within standard quantum theory. In AdS/CFT, this would mean that the completion of the semiclassical subalgebra to the complete boundary algebra has to be traced back to the emergent near horizon Hilbert space structure. The present investigations suggest that spacetime horizons, in general, may play a crucial role in restoring a long speculated ontology in quantum mechanics.
Cosmological features of Barrow Holographic Dark Energy (BHDE), a recent generalization of original Holographic dark energy with a richer structure, are studied in the context of DGP brane, RS II brane-world, and the cyclic universe. It is found that a flat FRW scenario with pressure less dust and a dark energy component described as BHDE can accommodate late time acceleration with Hubble horizon considered as infrared cut off even in the absence of interaction between the dark sectors. Statefinder diagnostic reveals that these model resemble $\Lambda CDM$ cosmology in future. It is found that BHDE parameter $\Delta$, despite its theoretically constrained range of values, is significant in describing the evolution of the universe, however, a classically stable cosmological model cannot be obtained in the RS-II and DGP brane. Viability of the models is also probed with observed Hubble data.
The Bethe-Salpeter equation is a non-perturbative, relativistic and covariant description of two-body bound states. We derive the classical Bethe-Salpeter equation for two massive point particles (with or without spin) in a bound gravitational system. This is a recursion relation which involves two-massive-particle-irreducible diagrams in the space of classical amplitudes, defined by quotienting out by symmetrization over internal graviton exchanges. In this context, we observe that the leading eikonal approximation to two-body scattering arises directly from unitarity techniques with a coherent state of virtual gravitons. More generally, we solve the classical Bethe-Salpeter equation analytically at all orders by exponentiating the classical kernel in impact parameter space. We clarify the connection between this classical kernel and the Hamilton-Jacobi action, making manifest the analytic continuation between classical bound and scattering observables. Using explicit analytic resummations of classical (spinless and spinning) amplitudes in momentum space, we further explore the relation between poles with bound state energies and residues with bound state wavefunctions. Finally, we discuss a relativistic analogue of Sommerfeld enhancement which occurs for bound state cross sections.
We introduce a novel method to generate a bank of gravitational-waveform templates of binary black hole (BBH) mergers for matched-filter searches in LIGO, Virgo and Kagra data.We derive a novel expression for the metric approximation to the distance between templates, which is suitable for precessing BBHs and/or systems with higher-order modes (HM) imprints and we use it to meaningfully define a template probability density across the parameter space. We employ a masked autoregressive normalizing flow model which can be conveniently trained to quickly reproduce the target probability distribution and sample templates from it. Thanks to the normalizing flow, our code takes a few {\it hours} to produce random template banks with millions of templates, making it particularly suitable for high-dimensional spaces, such as those associated to precession, eccentricity and/or HM. After validating the performance of our method, we generate a bank for precessing black holes and a bank for aligned-spin binaries with HMs: with only 5% of the injections with fitting factor below the target of 0.97, we show that both banks cover satisfactorily the space. Our publicly released code mbank will enable searches of high-dimensional regions of BBH signal space, hitherto unfeasible due to the prohibitive cost of bank generation.
Propagation of fermions in spacetime requires a spin connection, which can be split into a universal gravitational part and a non-universal ``contorsion'' part. The latter is non-dynamical and can be eliminated from the theory, leaving an effective four-fermion interaction with unknown coupling constants. The generic form of the contorsion-fermion coupling, and thus the four-fermion interaction, breaks chiral symmetry. This interaction affects all fermions -- in particular neutrinos passing through matter will notice a contribution to their effective Hamiltonian, just like the MSW effect coming from weak interactions, but diagonal in the mass basis rather than the flavor basis. Then there is a possibility that this geometrical contribution is not negligible for neutrinos passing through normal matter, provided the coupling constants are not too small. We calculate the matter potential due to this interaction and thus write the conversion and survival probabilities including its effect. We plot conversion probabilities of $\nu_\mu$ to $\nu_e$ and $\nu_\tau$ for a baseline of 1300 km, as well as their dependence on the CP phase, with and without the geometrical interaction. We also plot the survival probability of reactor $\bar{\nu}_e$ for different baselines.
We have investigated the decoherence time induced by the primordial gravitons with minimum uncertainty initial states. This minimum uncertainty condition allows the initial state to be an entanglement or, more generally, a superposition between a vacuum and an entanglement state. We got that for initial state entanglement, the decoherence time will last a maximum of 20 seconds, similar to the initial Bunch-Davies vacuum, and if the total graviton is greater than zero, the dimensions of the experimental setup system could be reduced. We also found that quantum noise can last much longer than vacuum or entanglement states for initial state superposition, which will be maintained for $\approx 10^{19}$ seconds.
We cut a general, static, spherically symmetric spacetime and paste its copy to make a wormhole with a thin shell of any barotropic fluid in general relativity. We show that the stability of the thin-shell wormhole is characterized by a set of circular photon orbits called an (anti)photon sphere in the original spacetime if a momentum flux passing through a throat is prohibited. Our result will be useful to classify the stability of the thin shell on the throat against linearized spherically symmetric perturbations.
As an effective theory, relativistic hydrodynamics is fixed by symmetries up to a set of transport coefficients. A lot of effort has been devoted to explicit calculations of these coefficients. Here we propose a shift in perspective: we deploy bootstrap techniques to rule out theories that are inconsistent with microscopic causality. What remains is a universal convex geometry in the space of transport coefficients, which we call the hydrohedron. The landscape of all consistent theories necessarily lie inside or on the edges of the hydrohedron. We analytically construct cross-sections of the hydrohedron corresponding to bounds on transport coefficients that appear in sound and diffusion modes for theories without stochastic fluctuations.
In this paper, we study the Minkowski-type inequality for asymptotically flat static manifolds $(M^{n}, g)$ with boundary and with dimension $ n < 8$ that was establishedby McCormick. First, we show that any asymptotically flat static $(M^{n},g)$ which achieves the equality and has CMC or equipotential boundary is isometric to a rotationally symmetric region of the Schwarzschild manifold. Then, we apply conformal techniques to derive a new Minkowski-type inequality for the level sets of bounded static potentials. Taken together, these provide a robust approach to detecting rotational symmetry of asymptotically flat static systems. As an application, we prove global uniqueness of static metric extensions for the Bartnik data induced by both Schwarzschild coordinate spheres and Euclidean coordinate spheres in dimension $n < 8$ under the natural condition of Schwarzschild stability. This generalizes an earlier result of Miao. We also establish uniqueness for equipotential photon surfaces with small Einstein-Hilbert energy. This is interesting to compare with other recent uniqueness results for static photon surfaces and black holes.
We reconsider the problem of a slowly rotating homogeneous star, or Schwarzschild star, when its compactness goes beyond the Buchdahl bound and approaches the gravastar limit $R\to 2M$. We compute surface and integral properties of such configuration by integrating the Hartle-Thorne structure equations for slowly rotating relativistic masses, at second order in angular velocity. In the gravastar limit, we show that the metric of a slowly rotating Schwarzschild star agrees with the Kerr metric, thus, within this approximation, it is not possible to tell a gravastar from a Kerr black hole by any observations from the spacetime exterior to the horizon.
This work investigates the impacts of energy-momentum conservation violation on the configuration of strange stars constraint with gravitational wave (GW) event GW190814 as well as eight recent observations of compact objects. The GW echoes from these interesting classes of compact objects are also calculated. To describe the matter of strange stars, we have used two different equations of state (EoSs): first an ad-hoc exotic EoS, the stiffer MIT Bag model and next realistic CFL phase of quark matter EoS. We choose Rastall gravity as a simple model with energy-momentum conservation violation with a set of model parameter values. Our results show that this gravity theory permits stable solutions of strange stars and the resulting structures can foster GW echoes. We illustrate the implication of the gravity theory and found that the negative values of the Rastall parameter result in more compact stellar configurations and lower GW echo frequency. With an increase in the Rastall parameter, both the compactness of the stellar configurations and echo time decrease. It is worth mentioning here that with the chosen set of some probable strange star candidates from observational data and also in light of GW 190814, we have evaluated the radii of stellar models. Also, the GW echo frequencies associated with strange stars are found to be in the range of {$\approx 9-27$ kHz} for both cases. {From this work, it is also inferred that the assumption regarding the equivalence of Rastall's theory to Einstein's theory is refuted as we have noticed many deviations in the physical properties of the considered compact stars.
The interaction between localized emitters and quantum fields, both in relativistic settings and in the case of ultra-strong couplings, requires non-perturbative methods beyond the rotating-wave approximation. In this work we employ chain-mapping methods to achieve a numerically exact treatment of the interaction between a localized emitter and a scalar quantum field. We extend the application range of these methods beyond emitter observables and apply them to study field observables. We first provide an overview of chain-mapping methods and their physical interpretation, and discuss the thermal double construction for systems coupled to thermal field states. Modelling the emitter as an Unruh-DeWitt particle detector, we then calculate the energy density emitted by a detector coupling strongly to the field. As a stimulating demonstration of the approach's potential, we calculate the radiation emitted from an accelerated detector in the Unruh effect, which is closely related to the thermal double construction as we discuss. We comment on prospects and challenges of the method.
We consider scalar perturbations of the Reissner--Nordstr\"{o}m family and the Kerr family. We derive a characteristic expression of the radiation field, at any given unit solid angle of future null infinity, and numerically show that its amplitude gets excited only in the extremal case. Our work, therefore, identifies an observational signature for extremal black holes. Moreover, we show that the source of the excitation is the extremal horizon instability and its magnitude is exactly equal to the conserved horizon charge.
We describe a mechanism in which the graviton acquires a mass from the functional measure without violating the diffeomorphism symmetry nor including St\"uckelberg fields. Since gauge invariance is not violated, the number of degrees of freedom goes as in general relativity. For the same reason, Boulware-Deser ghosts and the vDVZ disconinuity do not show up. The graviton thus becomes massive at the quantum level while avoiding the usual issues of massive gravity.
We investigate the vacuum expectation value of the surface energy-momentum tensor (SEMT) for a scalar field with general curvature coupling in the geometry of two branes orthogonal to the boundary of anti-de Sitter (AdS) spacetime. For Robin boundary conditions on the branes, the SEMT is decomposed into the contributions corresponding to the self-energies of the branes and the parts induced by the presence of the second brane. The renormalization is required for the first parts only and for the corresponding regularization the generalized zeta function method is employed. The induced SEMT is finite and is free from renormalization umbiguities. For an observer living on the brane, the corresponding equation of state is of the cosmological constant type. Depending on the boundary conditions and on the separation between the branes, the surface energy densities can be either positive or negative. The energy density induced on the brane vanishes in special cases of Dirichlet and Neumann boundary conditions on that brane. The effect of gravity on the induced SEMT is essential at separations between the branes of the order or larger than the curvature radius for AdS spacetime. In the large separation limit the decay of the SEMT, as a function of the proper separation, follows a power law for both massless and massive fields. For parallel plates in Minkowski bulk and for massive fields the fall-off of the corresponding expectation value is exponential.
We discuss the problem of canonical quantization of a free massive spinor field in the Schwarzschild spacetime. It is shown that a consistent procedure of canonical quantization of the field can be carried out without taking into account the internal region of the black hole, the canonical commutation relations in the resulting theory hold exactly and the Hamiltonian has the standard form. Spin sums are obtained for solutions of the Dirac equation in the Schwarzschild spacetime.
We study gravitational lensing of gravitational waves taking into account the spin of a graviton coupled with a dragged spacetime made by a rotating object. We decompose the phase of gravitational waves into helicity-dependent and independent components with spin optics, analyzing waves whose wavelengths are shorter than the curvature radius of a lens object. We analytically confirm that the trajectory of gravitational waves splits depending on the helicity, generating additional time delay and elliptical polarization onto the helicity-independent part. We exemplify monotonic gravitational waves lensed by a Kerr black hole and derive the analytical expressions of corrections in phase and magnification. The corrections are enhanced for longer wavelengths, potentially providing a novel probe of rotational properties of lens objects in low-frequency gravitational-wave observations in the future.
In this article, we consider a class of four-dimensional Einstein-Maxwell theory which is coupled non-minimally to a scalar field and the Gauss-Bonnet invariant. We mainly use the numerical methods to find the solutions to the theory, with the NUT twist. We find explicitly the numerical solutions to all of the field equations. To find the appropriate consistent numerical solutions, we use the the perturbative expansion of the fields asymptotically, as well as near horizon. The solutions describe the NUTty black holes with the scalar charge which also depend explicitly on the values of the non-minimal coupling constants. We provide a detailed numerical analysis of the solutions in terms of all existing parameters of the theory.
The merging of quantum information science with the relativity theory presents novel opportunities for understanding the enigmas surrounding the transmission of information in relation to black holes. For this purpose, we study the quantumness near a Schwarzschild black hole in a practical model under decoherence. The scenario we consider in this paper is that a stationary particle in the flat region interacts with its surroundings while another particle experiences free fall in the vicinity of a Schwarzschild black hole's event horizon. We explore the impacts of Hawking radiation and decoherence on the system under investigation and find that these effects can limit the survival of quantum characteristics, but cannot destroy them completely. Hence, the results of this study possess the potential to yield valuable insights into the comprehension of the quantum properties of a real system operating within a curved space-time framework.
The interior of a pure-state black hole is known to be reconstructed from the Petz map by collecting a sufficiently large amount of the emitted Hawking radiation. This was established based on the Euclidean replica wormhole, which comes from an ensemble averaging over gravitational theories. On the other hand, this means that the Page curve and the interior reconstruction are both ensemble averages; thus, there is a possibility of large errors. In the previous study [Bousso, Miyaji (2023)], it was shown that the entropy of the Hawking radiation has fluctuation of order $e^{-S_{\mathbf{BH}}}$, thus is typical in the ensemble. In the present article, we show that the fluctuations of the relative entropy difference in the encoding map and the entanglement fidelity of the Petz map are both suppressed by $e^{-S_{\mathbf{BH}}}$ compared to the signals, establishing the typicality in the ensemble. In addition, we also compute the entanglement loss of the encoding map.
Spin network technique is usually generalized to relativistic case by changing $SO(4)$ group -- Euclidean counterpart of the Lorentz group -- to its universal spin covering $SU(2)\times SU(2)$, or by using the representations of $SO(3,1)$ Lorentz group. We extend this approach by using inhomogeneous Lorentz group $\mathcal{P}=SO(3,1)\rtimes \mathbb{R}^4$, which results in the simplification of the spin network technique. The labels on the network graph corresponding to the subgroup of translations $\mathbb{R}^4$ make the intertwiners into the products of $SU(2)$ parts and the energy-momentum conservation delta functions. This maps relativistic spin networks to usual Feynman diagrams for the matter fields.
The Unruh vacuum is widely used as quantum state to describe black hole evaporation since near the horizon it reproduces the physical state of a quantum field, the so called in-vacuum, in the case the black hole is formed by gravitational collapse. We examine the relation between these two quantum states in the background spacetime of a Reissner-Nordstr\"om black hole (both extremal and not) highlighting similarities and striking differences.
This paper reviews the investigations on the vacuum expectation value of the current density for a charged scalar field in spacetimes with toroidally compactified spatial dimensions. As background geometries locally Minkowskian (LM), locally de Sitter (LdS) and locally anti-de Sitter (LAdS) spacetimes are considered. Along compact dimensions quasiperiodicity conditions are imposed on the field operator and the presence of a constant gauge field is assumed. The vacuum current has non-zero components only along compact dimensions. Those components are periodic functions of the magnetic flux enclosed by compact dimensions with the period equal to the flux quantum. For LdS and LAdS geometries and for small values of the length of a compact dimension, compared with the curvature radius, the leading term in the expansion of the the vacuum current along that dimension coincides with that for LM bulk. In this limit the dominant contribution to the mode sum for the current density comes from the vacuum fluctuations with wavelength smaller than the curvature radius and the influence of the gravitational field is weak. The effects of the gravitational field are essential for lengths of compact dimensions larger than the curvature radius. In particular, instead of the exponential suppression of the current density in LM bulk one can have power law decay in LdS and LAdS spacetimes.
While wormholes may be just as good a prediction of Einstein's theory as black holes, they are subject to severe restrictions from quantum field theory. In particular, a wormhole can only be held open by violating the null energy condition, calling for the existence of ``exotic matter," a condition that many researchers consider completely unphysical, enough to rule out macroscopic traversable wormholes. An equally serious problem is the enormous radial tension at the throat of a typical Morris-Thorne wormhole unless the wormhole has an extremely large throat size. It has been proposed that noncommutative geometry, an offshoot of string theory, may be the proper tool for addressing these issues. The purpose of this paper is two-fold: (1) to refine previous arguments to make a stronger and more detailed case for this proposal and (2) to obtain a complete wormhole solution from the given conditions.
We discuss back-reaction in the semiclassical treatment of quantum fields near a black hole. When the state deviates significantly from Hartle-Hawking, simple energetic considerations of back-reaction give rise to a characteristic radial distance scale $\sim (r_s^{2}G_N)^{1/D}$, below which some breakdown of effective field theory may occur.
We investigate the evolution of entanglement within an open, strongly coupled system interacting with a heat bath as its environment, in the frameworks of both the doubly holographic model and the Sachdev-Ye-Kitaev (SYK) model. Generally, the entanglement within the system initially increases as a result of internal interactions; however, it eventually dissipates into the environment. In the doubly holographic setup, we consider an end-of-the-world brane in the bulk to represent an eternal black hole hermalized by holographic matters. The reflected entropy between the bipartition of a large black hole exhibits a ramp-plateau-slump behavior, where the plateau arises due to the phase transition of the entanglement wedge cross-section before the Page time. In quantum mechanics, we consider a double copy of the SYK-plus-bath system in a global thermofield double state, resembling an eternal black hole interacting with an environment. The R\'enyi mutual information within the double-copied SYK clusters exhibits a ramp-plateau-slope-stabilizing behavior. The dynamic behaviors of the entanglement quantities observed in these two models are attributable to the competition between the internal interaction of the system and the external interaction with the baths. Our study provides a fine-grained picture of the dynamics of entanglement inside black holes before their Page time.
Recent observational data from the Event Horizon Telescope (EHT) collaboration provide convincing realistic evidence for the existence of black hole rotation. From a phenomenological perspective, a recently proposed stable rotating regular (SRR) black hole circumvents the theoretical flaws of the Kerr solution. For the purpose of obtaining observational signatures of this black hole, we study its gravitational lensing effect. In the strong field limit, we calculate the deflection angle of light, the radius of the photon sphere, and other observables. The observables include the relativistic image position, separation, magnification, and time delays between different images. Then, by modeling M87* and Sgr A* as the SRR black hole, we compute their observables and evaluate the deviation of the observables from the Kerr case. In the weak field limit, we calculate the light deflection angle of M87* and Sgr A* via the Gauss-Bonnet theorem (GBT). With the growth of deviation parameter $e$, the gravitational lensing effect in the weak field limit intensifies monotonically, and the gravitational lensing effect in the strong field limit changes dramatically only at high spins. Our research may contribute to distinguish between SRR black holes from Kerr black holes under higher-precision astronomical observations.
The generalized post-Keplerian parametrization for compact binaries on eccentric bound orbits is established at second post-Newtonian (2PN) order in a class of massless scalar-tensor theories. This result is used to compute the orbit-averaged flux of energy and angular momentum at Newtonian order, which means relative 1PN order beyond the leading-order dipolar radiation of scalar-tensor theories. The secular evolution of the orbital elements is then computed at 1PN order. At leading order, the closed form ``Peters & Matthews'' relation between the semi-major axis $a$ and the eccentricity $e$ is found to be independent of any scalar-tensor parameter, and is given by $a \propto e^{4/3}/(1-e^2)$. Finally, the waveform is obtained at Newtonian order in the form of a spherical harmonic mode decomposition, extending to eccentric orbits the results obtained in [JCAP 08 (2022) 008].
We develop a purely quantum theory based on the novel principle of relativity, termed the quantum principle of relativity, without introducing general relativity. We demonstrate that the essence of the principle of relativity can be naturally extended into the quantum realm, maintaining the identical structures of active and passive transformations. By employing this principle, we show that gravitational effects are naturally incorporated into the renormalizable theory, with general relativity emerging in the classical regime. We derive graviton propagators and provide several examples grounded in this novel theory.
The Equivalence Principle is considered in the framework of metric-affine gravity. We show that it naturally emerges as a Noether symmetry starting from a general non-metric theory. In particular, we discuss the Einstein Equivalence Principle and the Strong Equivalence Principle showing their relations with the non-metricity tensor. Possible violations are also discussed pointing out the role of non-metricity in this debate.
Top pair production is ideally suited to observe post-decay entanglement, thus providing a novel test of quantum mechanics. We provide top polarised decay amplitudes that can be used to compute semi-analytical predictions and, in particular, to better understand {\em why} the post-decay entanglement arises. We obtain predictions for the LHC, identifying general phase space regions where experimental measurements of $tW$ entanglement are feasible. We also give predictions for polarised $e^+ e^-$ collisions, focusing on the possibility that the post-decay $tW$ entanglement is larger than the $t \bar t$ one.
The first Edition of this book was released in 2000, just before the symposium ``Thirty Years of Supersymmetry'' was held at the William I. Fine Theoretical Physics Institute (FTPI) of the University of Minnesota. Founders and trailblazers of supersymmetry descended on FTPI, as well as a large crowd of younger theorists deeply involved in research in this area. Since then 23 years have elapsed and significant changes happened in supersymmetry (SUSY). Its history definitely needs an update. Such an update is presented below. The Second Edition of the revised collection will be released in 2024.
Recently, the LHCb collaboration has observed the decays $\Xi^0_{b}\to\Xi^+_{c}D^-_s$ and $\Xi^-_{b}\to\Xi^0_{c}D^-_s$. They measured the relative branching fractions times the ratio of beauty-baryon production cross-sections $\mathcal{R}(\frac{\Xi^0_b}{\Lambda_b})\equiv\frac{\sigma(\Xi_b^0)}{\sigma(\Lambda^0_b)}\times\frac{B(\Xi^0_{b}\to\Xi^+_{c}D^-_s)}{B(\Lambda^0_{b}\to\Lambda^+_{c}D^-_s)}$ and $\mathcal{R}(\frac{\Xi^-_b}{\Lambda_b})\equiv\frac{\sigma(\Xi^-_b)}{\sigma(\Lambda^0_b)}\times\frac{B(\Xi^-_{b}\to\Xi^0_{c}D^-_s)}{B(\Lambda^0_{b}\to\Lambda^+_{c}D^-_s)}$. Once the ratio $\frac{\sigma(\Xi_b^0)}{\sigma(\Lambda^0_b)}$ or $\frac{\sigma(\Xi_b^-)}{\sigma(\Lambda^0_b)}$ is known, one can determine the relative branching fractions which can be used to exam the mixing of $\Xi_c$ and $\Xi'_c$. In previous literature, $\Xi_c$ and $\Xi'_c$ were assumed to belong to SU(3)$_F$ antitriple and sextet, respectively. However, recent experimental measurements such as the ratio $\Gamma(\Xi_{cc}\to\Xi_c\pi^+)/\Gamma(\Xi_{cc}\to\Xi'_c\pi^+)$ indicate the spin-flavor structures of $\Xi_{c}$ and $\Xi'_{c}$ are a mixture of $\Xi^{\bar 3}_{c}$ and $\Xi^{6}_{c}$. The exact value of mixing angle $\theta$ is still under debate. In theoretical models, the mixing angle was fitted to be about $16.27^\circ\pm2.30^\circ$ or $85.54^\circ\pm2.30^\circ$ based on decay channels $\Xi_{cc} \to\Xi^{(')}_{cc} $. While in lattice calculation, a small angle ($1.2^\circ\pm0.1^\circ$) is preferred. To address such discrepancy and test the mixing of $\Xi_c$ and $\Xi'_c$, here we propose the analysis of semileptonic and non-leptonic decays of $\Xi_{b}\to\Xi_{c}$ and $\Xi_{b}\to\Xi^{'}_{c}$. We calculate the decay rate of $\Xi_{b}\to\Xi_{c}$ and $\Xi_{b}\to\Xi^{'}_{c}$ based on light-front quark model and study the effect of the mixing angle on the ratios of weak decays $\Xi_{b}\to\Xi_{c}$ and $\Xi_{b}\to\Xi^{'}_{c}$.....
In this paper, we solve the bound state problem for Varshni-Hellmann potential via a useful technique. In our technique, we obtain the bound state solution of the Schrodinger equation for the Varshni-Hellmann potential via ansatz method. We obtain the energy eigenvalues and the corresponding eigen-functions. Also, the behavior of the energy spectra for both the ground and the excited state of the two body systems is illustrated graphically. The similarity of our results to the accurate numerical values is indicative of the efficiency of our technique.
Dynamical chiral symmetry restoration for higher number of light quark flavors $N_f$ and breaking for higher number of colors $N_c$ implies the suppression and enhancement of the dynamically generated quark mass. The study of various larger values of number of colors and flavors may have greater impact on the internal structure of light hadrons. In this work, we study the properties of the pion and kaon, such as mass, condensate, and leptonic decay constant, for various $N_f$ and $N_c$. We use the symmetry-preserving vector-vector flavor-dependent contact interaction model of quark. The dynamical quark masses are calculated by using the Schwinger-Dyson equation (SDE). The masses of the pion and kaon for different values of $N_f$ and $N_c$ are determined using the homogeneous Bethe-Salpeter equation. For fixed $N_f=2$ and $N_c$ is increased, the dynamically generated quark mass ( mass of up and down quarks), strange quark mass, meson in-condensate, and decay constant, all increases. The pion mass remains approximately constant until $N_c$ reaches around 6.5, after which it grows rapidly. On the other hand, the kaon mass increases slowly with increasing $N_c$ until it reaches approximately $N_c=7.5$, beyond which it rises quickly. When $N_c=3$ is fixed at and various values of $N_f$ are considered, all the parameter values decrease as a function of $N_f$, except for the pion and kaon mass, which increase above a critical value of $N_f$ around $8$. This is the region where chiral symmetry is restored, and the pion and kaon behave as free particles, similar to their behavior in the presence of a heat bath. The results obtained for fixed $N_f=2$ and $N_c=3$ are fairly in decent agreement with experimentally calculated statistics and previous model calculations based on the Schwinger-Dyson equation (SDE) and Bethe-Salpeter equation (BSE).
We explore the squeezed back-to-back correlation (SBBC) and investigate how the squeezing effect influences the Hanbury Brown-Twiss (HBT) interferometry using an expanding Gaussian source with non-zero width. The SBBC and HBT of $D^0$ and $\phi$ mesons with finite in-medium widths are studied. The expanding flow of the source may enhance the SBBC strength of $D^0{\bar D}^0$ and $\phi\phi$ in the low momentum region but suppress the SBBC in the larger momentum region. The squeezing effect suppresses the influence of flow on the HBT radii, which is significant for two identical bosons with large pair momentum or with large mass. Due to the squeezing effect, the relationship between the HBT radii and the pair momentum exhibits non-flow behavior for $D^0D^0$ pair. Likewise, non-flow behavior also appears in the HBT radii of $\phi\phi$ with large pair momentum. This phenomenon may bring new insights for studying the squeezing effect.
The EPOS4 project is an attempt to construct a realistic model for describing relativistic collisions of different systems, from proton-proton ($pp$) to nucleus-nucleus ($AA$), at energies from several TeV per nucleon down to several GeV. We argue that a parallel scattering formalism (as in EPOS4) is relevant for primary scatterings in AA collisions above 4 AGeV, whereas sequential scattering (cascade) is appropriate below. We present briefly the basic elements of EPOS4, and then investigate heavy ion collisions from 62.4 AGeV down to 4 AGeV, to understand how physics changes with energy, studying in particular the disappearance of the fluid component at low energies.
In this work we evaluate the $X(3872)$ to $ \psi (2S) $ yield ratio ($N_X/N_{\psi(2S)}$) in Pb Pb collisions, taking into account the interactions of the $\psi (2S) $ and $ X(3872)$ states with light mesons in the hadron gas formed at the late stages of these collisions. We employ an effective Lagrangian approach to estimate the thermally-averaged cross sections for the production and absorption of the $\psi(2S)$ and use them in the rate equation to determine the time evolution of $N_{\psi(2S)}$. The multiplicity of these states at the end of mixed phase is obtained from the coalescence model. The multiplicity of $X(3872)$, treated as a bound state of $(D\bar D^{*} + c.c.)$ and also as a compact tetraquark, was already calculated in previous works. Knowing these yields, we derive predictions for the ratio ($N_X/N_{\psi(2S)}$) as a function of the centrality, of the center-of-mass energy and of the charged hadron multiplicity measured at midrapidity $[dN_{ch}/d\eta \,(\eta<0.5)]$. Finally, we make predictions for this ratio in Pb Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV to be measured by the ALICE Collaboration in the Run 3.
In collider physics, parton distribution functions (PDFs) play a crucial role in computing theoretical cross sections for scattering reactions. This study explores how different experimental data sets influence extracted PDFs in CTEQ-TEA and MSHT NNLO PDF analyses. To gauge the impact of experimental data, including the HERA and ZEUS combined charm and beauty production, LHCb 7 TeV charm and beauty production, and CMS 2.76 TeV W+c production, I utilize the $L_2$ sensitivity in the Hessian framework as a visual representation of their respective impacts. This sensitivity quantifies the statistical pulls on individual data sets against the best-fit PDFs, facilitating the identification of tensions among competing data sets. Using the QCD fitting framework xFitter, I extract the necessary values for plotting $L_2$ sensitivities for eight distinct data sets implemented in the program, employing recent PDF sets from the CTEQ-TEA and MSHT groups. The computed $L_2$ sensitivities estimate the potential impact of the examined data sets.
Vector-like quarks~(VLQs) are a common feature of many scenarios of new physics beyond the Standard Model~(SM), which generally decay into a SM third-generation quark with a SM gauge boson, or a Higgs boson. The presence of a new exotic decay mode of VLQs will reduce the branching ratios of these standard decay modes and thus relax the current mass exclusion limits from LHC experiments. Based on a model-independent framework, we investigate the prospect of discovering the pair production of the weak-singlet VLQ-$B$ at the future 3-TeV Compact Linear Collider~(CLIC), by focusing on the final states including one $Z$ boson and four $b$-jets via two types of modes: $Z\to \ell^{+}\ell^{-}$ and $Z\to \nu\bar{\nu}$. By performing a rapid detector simulation of the signal and background events, and considering the initial state radiation and beamstrahlung effects, the exclusion limit at the 95\% confidence level and the $5\sigma$ discovery prospects are respectively obtained on the branching ratio of $B\to bZ$ and the VLQ-$B$ masses at the future 3-TeV CLIC with an integrated luminosity of 5 ab$^{-1}$.
Gravitational form factors of hadrons provide information on mass and pressure distributions in the hadrons, and they have been investigated by generalized parton distributions (GPDs). The GPDs also contain information on internal compositions of hadron spins. Understanding on the origin of hadron masses, pressures, and spins is an important topic not only in hadron physics but also as fundamental physics, and it should be clarified by the GPD studies. The spacelike and timelike GPDs have been measured at charged-lepton accelerator facilities, for example, by the virtual Compton scattering and the two-photon process, respectively. In this work, we show the $\pi^\pm$ and $\pi^0$ production cross sections in neutrino (antineutrino) reactions $\nu \,(\bar\nu) + N \to \ell + \pi + N'$ for measuring the GPDs of the nucleon by using the theoretical formalism of Pire, Szymanowski, and Wagner. The $\pi^\pm$-production cross sections are useful for determining gluon GPDs, whereas the $\pi^0$ production probes quark GPDs. In particular, we show the roles of the pion- and rho-pole terms, the contribution from each GPD term ($H$, $E$, $\tilde H$, $\tilde E$), the effects of the gluon GPDs $H_g$ and $E_g$, and the effects of the reaction energy on the neutrino cross sections. The $\pi^0$-production cross section is sensitive to the quark GPDs including the pion- and rho-pole GPD terms in the Efremov-Radyushkin-Brodsky-Lepage region. These cross sections could be measured at Fermilab in future. The neutrino GPD studies will play a complementary role to the projects of charged-lepton and hadron reactions for determining the accurate GPDs.
The Abelian decomposition of QCD reveals two types of gluons: color-neutral ``neurons" and color-carrying ``chromons". This classification does not alter the overall properties of QCD, but the investigation of different types of gluon dynamics is necessary. By employing the Cho-Duan-Ge decomposition theorem, we have derived dynamic evolution equations for two types of gluons by using the time-ordered perturbation theory. We propose that the new equations are compatible with the DGLAP equations, requiring only the separate contributions of neurons and chromons to be summed. Surprisingly, with the evolution to high $Q^2$, the ratio of the number of chromons to neurons is approximately 3:1 in small-$x$ region regardless of the inputs at evolution starting point. The new gluon dynamic equations reevaluate the gluon distribution functions and allow for a elaborate inverstigation of the distinct contributions of gluons in high-energy collisions.
Theoretical physicists describe nature by i) building a theory model and ii) determining the model parameters. The latter step involves the dual aspect of both fitting to the existing experimental data and satisfying abstract criteria like beauty, naturalness, etc. We use the Yukawa quark sector as a toy example to demonstrate how both of those tasks can be accomplished with machine learning techniques. We propose loss functions whose minimization results in true models that are also beautiful as measured by three different criteria - uniformity, sparsity, or symmetry.
The recent measurement of $\mathcal{B}(B^+\to K^+\nu\bar{\nu})$ by Belle-II reveals a $2.8~\sigma$ deviation from the Standard Model (SM) prediction. Combining this with a prior Belle measurement of $\mathcal{B}(B^{0}\to K^{\ast0}\nu\bar{\nu})$, the upper bound of the ratio $\mathcal{B}(B^{0}\to K^{\ast0}\nu\bar{\nu})/\mathcal{B}(B^+\to K^+\nu\bar{\nu})$ is notably smaller than the SM prediction. In this work, tensions are solved within the framework of Standard Model Effective Field Theory (SMEFT). Flavor observables, described by Low-Energy Effective Field Theory (LEFT) operators, are interconnected by SMEFT at the electroweak scale. Utilizing a set of only four SMEFT operators, the FCNC process $b\to s\nu\bar{\nu}$ is correlated with $b\to s\ell^+\ell^-$, $b\to u_i\ell\bar{\nu}$, $u_j\to s\ell\bar{\nu}$, $u_j\to u_i\nu\bar{\nu}$, and $u_j\to u_i\ell^+\ell^-$. Subsequently, we obtain the latest ranges of Wilson coefficients for these four operators through a global fit that accommodates flavor anomalies such as $R_{K^{(\ast)}}$, $R_{D^{(\ast)}}$, and $\mathcal{B}(B\to K^{(\ast)}\nu\bar{\nu})$. Our findings reveal that predictions for $\mathcal{B}(B^+\to \tau^+\nu_\tau)$ and $\mathcal{B}(D_s^+\to \tau^+\nu_\tau)$ align well with measured values from Belle and BESIII, based on the fitted coefficients. The predicted branching fraction for $B^0\to K^{\ast0}\nu\bar{\nu}$ is $(1.42\pm 0.74)\times 10^{-5}$, closely approaching the current experimental upper limit. Anticipation surrounds the rare decay $B_s\to \tau^+ \tau^-$, expected in the near future with a branching fraction on the order of $10^{-4}$.
Radiative decays X --> psi(1S) + gamma and X --> psi(2S) + gamma might be expected to have a ratio of branching fractions following the phase space volumes ratio. However data suggest the opposite, indicating a value for R=B(X --> psi^prime + gamma) / B(X --> psi +gamma) consistently larger than one. In this paper we present a calculation of R for both a compact Born-Oppenheimer cc-bar q-qbar state and a DD^* molecule. In the former case R~1 or larger is found, a value to be confronted with forthcoming high statistics data analyses. In the molecular picture, with D and D^* mesons described by the universal wave function used by Voloshin, Braaten and Kusunoki, we find that R would be of order 10^-2. A more precise experimental measure would be extremely helpful in clarifying the true nature of the X(3872).
In this article, we investigate the angular distribution of the \BDlnu process to search for New Physics signals. The Belle collaboration has analysed it to constraint $V_{cb}$ and the $B\to D^*$ form factors, under the assumption of the Standard Model. With the newly released lattice QCD data, we can perform a simultaneous fit of the form factors, $V_{cb}$ as well as of furthermore new physics parameters. We use the untagged Belle data and the lattice data to constrain right-handed new physics. In addition, we also generate unbinned pseudo-dataset and perform a sensitivity study on more general new physics models, along with the lattice data.
The chiral perturbation theory (ChPT) of pions is extended to include vector mesons as well as pertinent degrees of freedom. By counting the typical momentum scale of vector mesons as order of $Q$ and vector meson masses as of the order of $\Lambda_\chi$, a consistent theory could be obtained. The explicit renormalization procedure of the theory is presented for the form factors of the pion up to one-loop accuracy. The resulting theory prediction for the form factors is in good agreement with the experimental data for a wide range of momentum transfers. The vector-meson dominance mechanism is also discussed in the systematic framework of ChPT.
The relic density of dark matter in the $\Lambda$CDM model restricts the parameter space for a cosmological axion field, constraining the axion decay constant, the initial amplitude of the axion field and the axion mass. It is shown via lattice simulations how the relic density of axion-like particles with masses close to the one of the QCD axion is affected by axion-gauge field interactions and by initial axion inhomogeneities. For pre-inflationary axions, once the Hubble parameter becomes smaller than the axion mass, the latter starts to oscillate, and part of its energy density is spent producing gauge fields via parametric resonance. If the gauge fields are dark photons and Standard Model photons, the energy density of dark photons becomes higher than the one of the axion, while the high conductivity of the primordial plasma damps the oscillations of the photon field. Such a scenario allows for the production of small-scale, primordial magnetic fields, and it is found that the relic density of axions with a low decay constant are within the bounds set by the $\Lambda$CDM model, while GUT-scale axions are far too abundant. It is also shown that initial inhomogeneities of the axion field can change substantially the gauge field production, boosting or suppressing (depending on the axion parameters and couplings) the magnetogenesis mechanism with respect to an homogeneous axion field. It is found that when the axion mass is far lighter than the QCD axion model and the initial axion field is inhomogeneous, weak but cosmologically relevant magnetic field seeds can be generated on scales of the order of $0.1$ kpc.
In this research, we propose a modified version of the 3-3-1 model, incorporating a type I+II seesaw mechanism and Z4 discrete symmetry, as a framework for investigating lepton flavor-violating (LFV) decays. This model successfully yields the left-handed neutrinos mass square difference in the eV scale, with specific values of mass square differences; and generates mixing angles that align with experimental data. Furthermore, we develop SARAH and SPheno algorithms tailored for our modified model, enabling us to estimate the magnitude of LFV observables. Our calculations indicate favorable results for various LFV branching ratios. These findings demonstrate improved agreement with experimental measurements compared to previously reported results, which typically fall within the range of 10^-2 to 10^-6.
We present results for the short-distance window observable of the hadronic vacuum polarization contribution to the muon $g-2$, computed via the time-momentum representation (TMR) in lattice QCD. A key novelty of our calculation is the reduction of discretization effects by a suitable subtraction applied to the TMR kernel function, which cancels the leading $x_0^4$-behaviour at short distances. To compensate for the subtraction, one must substitute a term that can be reliably computed in perturbative QCD. We apply this strategy to our data for the vector current collected on ensembles generated with $2+1$ flavours of O($a$)-improved Wilson quarks at six values of the lattice spacing and pion masses in the range $130-420\,$MeV. Our estimate at the physical point contains a full error budget and reads $(a_\mu^{\rm hvp})^{\rm SD}=68.85(14)_{\rm stat}\,(42)_{\rm syst}\cdot10^{-10}$, which corresponds to a relative precision of 0.7\%. We discuss the implications of our result for the observed tensions between lattice and data-driven evaluations of the hadronic vacuum polarization.
We show that the N(1440) Roper resonance naturally appears in the nuclear model with explicit mesons as a structure in the continuum spectrum of the physical proton which in this calculation is made of a bare nucleon dressed with a pion cloud.
The Fried-Yennie gauge is a covariant gauge for which the mass-shell renormalization procedure can be performed without introducing spurious infrared divergences to the theory. It is usually applied in calculations in regular Quantum-Electrodynamics (QED), but it is particularly interesting to be employed in the framework of pseudo-QED (PQED), where fermions are constrained to 2+1 dimensions while external fields interacting with these fermions live in the bulk of a 3+1 space. In this context, the gauge parameter can be adjusted to match the power of the external momentum in the denominator of the photon propagator, simplifying the infrared region without the need of a photon mass. In this work we apply for the first time this machinery to PQED, generalizing the procedure to calculate the self energy in arbitrary dimensions, allowing of course for different dimensionality of fermions and gauge fields.
Plasmon, a collective mode of electronic excitation in semiconductor materials, provides a unique avenue for the detection of light dark matter (DM). In this work, we first generalize the theoretical formalism of plasmon to treat the relativistic DM particles. We demonstrate that the plasmon resonance effect for sub-MeV DM can be significantly enhanced, particularly in scenarios of boosted DM with a light mediator. Utilizing the first data from SENSEI at SNOLAB, we derive a new strong limit on the sub-MeV DM-electron scattering cross section, which is more stringent than those from liquid detectors.
We calculate the form factors for the baryon number violation process of a heavy-flavor baryon decaying into a pseudoscalar meson and a lepton. In the framework of the Standard Model effective field theory, the leptoquark operators at the bottom quark scale, whose matrix elements define the form factors, are derived by integrating out the high energy physics. Under the QCD factorization approach, the form factors of the baryon number violation process at leading power can be factorized into the convolution of the long-distance hadron wave function as well as the short-distance hard and jet functions representing the hard scale and hard-collinear scale effects, separately. Based on measurements of the baryon number violation process by LHCb, we further impose constraints on the new physics constants of leptoquark operators.
Flavour changing neutral current (FCNC) processes are described by loop diagrams in the Standard Model (SM), while in 331 models, based on the gauge group $\text{SU}(3)_C \times \text{SU}(3)_L \times \text{U}(1)_X$, they are dominated by tree-level exchanges of a new heavy neutral gauge boson $Z'$. Exploiting this feature, observables related to FCNC decays of $K$, $B_d$ and $B_s$ mesons can be considered in several variants of 331 models. The variants are distinguished by the value of a parameter $\beta$ that plays a key role in this framework. Imposing constraints on the $\Delta F = 2$ observables, we select possible ranges for the mass of the $Z'$ boson in correspondence to the values $\beta = \pm k / \sqrt{3}$, with $k = 1, 2$. The results are used to determine the impact of 331 models on $b \to s$ processes and on the correlations among them, in the light of new experimental data recently released.
Relying on the polynomiality property of generalized parton distributions, which roots on Lorentz covariance, we prove that it is enough to know them at vanishing- and low-skewness within the DGLAP region to obtain a unique extension to their entire support up to a D-term. We put this idea in practice using two methods: Reconstruction using artificial neural networks and finite-elements methods. We benchmark our results against standard models for generalized parton distributions. In agreement with the formal expectation, we obtain a very accurate reconstructions for a maximal value of the skewness as low as 20% of the longitudinal momentum fraction. This result might be relevant for reconstruction of generalized parton distribution from experimental and lattice QCD data, where computations are for now, restricted in skewness.
We propose an orbifold lattice formulation of QCD suitable for quantum simulations. The advantages come from the use of noncompact variables that makes qubitization and truncated Hamiltonian very simple. It is shown that SU(3) gauge group and quarks in fundamental representation can be implemented straightforwardly.
Discrete symmetries play an important role in particle physics with violation of CP connected to the matter-antimatter imbalance in the Universe. We report the most precise test of P, T and CP invariance in decays of ortho-positronium, performed with methodology involving polarization of photons from these decays. Positronium, the simplest bound state of an electron and positron, is of recent interest with discrepancies reported between measured hyperfine energy structure and theory at the level of $10^{-4}$ signaling a need for better understanding of the positronium system at this level. We test discrete symmetries using photon polarizations determined via Compton scattering in the dedicated J-PET tomograph on an event-by-event basis and without the need to control the spin of the positronium with an external magnetic field, in contrast to previous experiments. Our result is consistent with QED expectations at the level of 0.0007 and one standard deviation.
We present a gauge and Lorentz invariant effective field theory model for the interaction of a charged scalar matter field with a magnetic monopole source, described by an external magnetic current. The quantum fluctuations of the monopole field are described effectively by a strongly-coupled ``dual'' $U_{\rm d}(1)$ gauge field, which is independent of the electromagnetic $U_{\rm em}(1)$ gauge field. The effective interactions of the charged matter with the monopole source are described by a gauge invariant mixed Chern-Simons-like (Pontryagin-density) term between the two $U(1)$ gauge fields. The latter interaction coupling is left free, and a Lattice study of the system is performed with the aim of determining the phase structure of this effective theory. Our study shows that, in the spontaneously-broken-symmetry phase, the monopole source triggers, via the mixed Chern-Simons term, which is non-trivial in its presence, the generation of a dynamical singular configuration (magnetic-monopole-like) for the respective gauge fields. The scalar field also behaves in the broken phase in a way similar to that of the scalar sector of the `t Hooft-Polyakov monopole.
The subject of this thesis is the construction of an approximation for the next-to-next-to-next-to leading order (N^3LO) deep inelastic scattering (DIS) massive coefficient function of the gluon for F2 in heavy quark pair production. Indeed, this object is one of the ingredients needed for the construction of any variable flavour number (factorization) scheme at O(alphas^3). The construction of such scheme is crucial for the improvement of the accuracy of the extraction of the parton distribution functions from the experimental data, that in turn will provide an improvement of the accuracy of all the theoretical predictions in high energy physics. Despite the function we are interested in is not known exactly, its expansion in some kinematic limits is available. In particular the high-scale limit (Q^2 >> m^2), high-energy limit (z->0, where z is the argument of the coefficient function) and threshold limit (z->zmax=1/(1+4m^2/Q^2)) of the exact coefficient function are all known, with the exception of some terms that we will provide in approximate form. Therefore, combining these limits in a proper way, we will construct an approximation for the unknown term of the N^3LO gluon coefficient function, that describes the exact curve in the whole range of z. Since other approximations for the N^3LO gluon coefficient functions are present in the literature, we will conclude by comparing our final approximate coefficient functions with such approximations. We will show a comparison both for the NNLO, whose exact function is known, and for the N^3LO. With our approach, we expect our results to be more accurate than previous approximations, thus providing a sufficient precision for a complete description of DIS at N^3LO and the consequent determination of N^3LO PDFs.
We discuss the possibility that threshold photoproduction of $\eta_{c,b}$ may be sensitive to the pseudovector $1^{+-}$ glueball exchange. We use the holographic construction to identify the pseudovector glueball with the Kalb-Ramond field, minimally coupled to bulk Dirac fermions. We derive the holographic C-odd form factor and its respective charge radius. Using the pertinent Witten diagrams, we derive and analyze the differential photoproduction cross section for $\eta_{c,b}$ in the threshold regime, including the interference from the dual bulk photon exchange with manifest vector dominance. The possibility of measuring this process at current and future electron facilities is discussed.
Functional forms of the neutron star Equation of State (EoS) are required to extract the viable EoS band from neutron star observations. Realistic nuclear EoS, containing deconfined quarks or hyperons, present nontrivial features in the speed of sound such as bumps, kinks, and plateaus. Using modified Gaussian processes to model EoS with nontrivial features, we show in a fully Bayesian analysis incorporating measurements from X-ray sources, gravitational wave observations, and perturbative QCD results that these features are compatible with current constraints. We find nontrivial behavior in the EoS plays a role in understanding the possible phase structure of neutron stars at densities around 2 $n_{\rm sat}$.
Hybrid leptogenesis framework combining type I and type II seesaw mechanism for neutrino mass necessarily include scattering topologies involving both the scalar triplet and the right handed neutrino. We demonstrate that a systematic inclusion of these mixed scatterings can significantly alter the evolution of the number densities leading to an order of magnitude change in the predicted value of present-day asymmetry. We provide quantitative limit on the degeneracy of the seesaw scales where the complete analysis becomes numerically significant, limiting the validity of leptogenesis being dominated by the lightest seesaw species.
We compute the full one-loop radiative corrections for charged scalar pair production $e^{+}e^{-}\to H^{+}H^{-}$ in the inert doublet model. The on-shell renormalization scheme has been used. We take into account both the weak contributions as well as the soft and hard QED corrections. We compute both the real emission and the one-loop virtual corrections using the Feynman diagrammatic method. The resummed cross section is introduced to cure the Coulomb singularity which occurs in the QED corrections. We have analyzed the parameter space of the inert doublet model in three scenarios after taking into account theoretical constraints, the collider experimental bounds, and dark matter search bounds as well. It is found that the weak interaction dominates the radiative corrections, and its size is determined by the triple Higgs coupling $\lambda_{h^0 H^+ H^-}$, which is further connected to the mass of the charged scalar. In the scenario where all the constraints are taken into account, we find that for $\sqrt{s}=250$ GeV and $\sqrt{s}=500$ GeV, the weak corrections are around $-6\% \sim-5\%$ and $-10\% \sim -3\%$, respectively. While for $\sqrt{s}=1000$ GeV, the weak corrections can reach $-15\% \sim +25\%$. The new feature is that the weak corrections can be positive near the threshold when the charged scalar is heavier than 470 GeV. Six benchmark points for future collider searches have been proposed.
In this work, we investigate the impact of neutrino decay in the presence of Non-Standard Interactions (NSI) along with the effects of the Majorana phase on neutrino decay in matter in the context of two-flavor neutrino oscillations. These effects are studied on neutrino oscillation probabilities $P_{\alpha \beta} \equiv P(\nu_{\alpha} \to \nu_{\beta})$, and the difference $\Delta P_{\alpha \beta} \equiv P(\nu_{\alpha} \to \nu_{\beta}) - P(\bar {\nu}_{\alpha} \to \bar{\nu}_{\beta})$ for several accelerator and reactor neutrino experiments. We find that for $P_{\alpha \beta}$, the influence of the Majorana phase on decay in matter can be replicated by the simultaneous presence of both decay and NSI. However, precise measurements of the $P_{\alpha \beta}$ and $\Delta P_{\alpha\beta}$ observables have the potential to unequivocally identify the presence of the Majorana phase by discerning its effects from the concurrent presence of both decay and NSI.
We review the theory and phenomenology of isosinglet vector-like quarks (VLQs). In recent years, interest in VLQs has been increasing, due to their contributions to new physics effects that can be tested in experiments at LHC and High-Luminosity LHC. The similarities of models with isosinglet VLQs and the seesaw framework in the leptonic sector are pointed out. The existence of VLQs leads to flavour-changing neutral currents at tree level and deviations from unitarity of the CKM matrix, introducing rich phenomenological implications. These new effects are naturally suppressed by the masses of the new quarks, that are constrained to be above the electroweak scale. In addition, striking new effects can be achieved with the inclusion of an extra complex scalar singlet. Such a minimal extension of the SM can give rise to new sources of CP violation with profound theoretical implications, allowing for a solution to the strong CP problem and a possible explanation for the baryon asymmetry of the Universe. We list and explain strong motivations to consider this class of models. We also briefly review how models with VLQs can be matched to the SM effective field theory (SMEFT). A detailed analysis of flavour observables that can be affected by the presence of VLQs is presented. Current bounds from collider searches of VLQs are summarized. We point out that the discovery of VLQs can be within the reach of present or future colliders being planned.
We examine the couplings of quarkonium hybrids to heavy-light meson pairs in the Born-Oppenheimer approximation for QCD. The lowest hybrid multiplets consist of bound states of the $\Pi_u$ and $\Sigma_u^-$ potentials. We find that the $\Sigma_u^-$ potential can couple to pairs of $S$-wave mesons through string breaking, while the $\Pi_u$ potential cannot. From this observation, we derive model-independent selection rules that contradict previous expectations that quarkonium hybrids are forbidden to decay into pairs of $S$-wave mesons. These Born-Oppenheimer selection rules are consistent with the partial decay widths of the lowest charmonium hybrid with exotic quantum numbers $J^{PC}=1^{-+}$ recently calculated in lattice QCD.
It is essential to directly investigate the self-couplings of gauge bosons in the Standard Model (SM) due to its non-Abelian nature, as these couplings play a significant role in comprehending the gauge structure of the model. The discrepancies between the Standard Model's expectations and the measured value of gauge boson self-couplings would serve as strong evidence towards the existence of new physics phenomena that extend beyond the Standard Model. Such deviations could provide valuable insights into the nature of new physics and potentially lead to a deeper understanding of fundamental particles and their interactions. In this study, we examine the sensitivities of anomalous couplings associated with dimension-8 operators that affect the $\gamma \gamma \gamma \gamma$ and $Z \gamma \gamma \gamma$ quartic vertices. The study focuses on the process $e^- \gamma \to e^-\gamma\gamma$ with the incoming photon under Weizs\"acker-Williams approximation at the stage-3 scenerio of Compact Linear Collider (CLIC) that is refer to a CoM energy of 3 TeV. Due to the CLIC options, we take into account the both unpolarized and $\mp80\%$ polarized electron beam with the related integrated luminosities of ${\cal L}=5, 4, 1$ $\rm ab^{-1}$ under the systematic uncertainties of $\delta_{sys}=0, 3, 5$. Obtained sensitivities on the anomalous quartic gauge couplings (aQGCs) for the process $e^- \gamma \to e^-\gamma\gamma$ at $\sqrt{s}= 3$ TeV and various polarizations, are improved by a factor of 2-200 times better for the couplings $f_{T,j}/\Lambda^4$ compared with the experimental results.
The internal image of the proton is unveiled by examining the generalized parton distributions (GPDs) at zero skewness, within the basis light-front quantized environment. Several distributions emerge when a quark is sampled with different currents depending upon the helicity arrangements of the active quark and the proton target. We investigate six of the eight leading-twist proton GPDs of the valence quarks, the helicity conserving distributions $(H, E, \tilde{H})$ and the helicity non-conserving $(H_T,E_T,\tilde{H}_T)$ distributions at skewness set to zero ($\zeta=0$). We consider purely transverse momentum transfer and, hence, obtain results describe only the proton's two-dimensional structure in the transverse plane. We present the Mellin moments of these distribution functions, where the first moment produces a form factor and the second Mellin moments help extract the information on partonic contributions to the hadronic angular momentum. We compare our results for the Mellin moments with those from lattice QCD and other approaches where available. We also present the GPDs in transverse position space.
In a pure inverse seesaw framework, achieving a substantial lepton asymmetry that can be converted into the observed baryon asymmetry of the Universe is extremely challenging. The difficulty arises primarily due to two reasons, (i) partial cancellation of the lepton asymmetries associated with the components of a pseudo-Dirac pair, and (ii) strong wash out caused by the inverse decays. In this work we offer two possible resolutions to overcome the above mentioned challenges considering a (3,3) ISS framework. Our first proposal is based on the assumption of a non-standard cosmological era in the pre-BBN epoch, that triggers a faster expansion of the Universe, thereby reducing the washout by several orders of magnitude. The second proposition is an alternative of first which considers a quasi-degenerate mass spectrum for the singlet heavy neutrinos, resulting into a larger order of lepton asymmetry that survives the impact of strong washout to account for the observed BAU. The viable parameters space, as obtained can be tested at present and future Lepton Flavour Violation experiments {\it e.g.} MEG and MEG II.}
The $\tau$ lepton anomalous magnetic moment: $a_\tau = \frac{g_{\tau}-2}{2}$ was measured, so far, with a precision of only several percents despite its highly sensitivity to physics beyond the Standard Model such as compositeness or Supersymmetry. A new study is presented to improve the sensitivity of the $a_\tau $ measurement with photon-photon interactions from ultra-peripheral lead-lead collisions at LHC. The theoretical approach used in this work is based on an effective Lagrangian and on a photon flux implemented in the MadGraph5 Monte Carlo simulation. Using a multivariate analysis to discriminate the signal from the background processes, a sensitivity to the anomalous magnetic moment $\rm{a_{\tau}}$ = 0 $_{+0.011} ^{-0.019}$ is obtained at 95\% CL with a dataset corresponding to an integrated luminosity of 2 nb$^{-1}$ of lead-lead collisions and assuming a conservative 10\% systematic uncertainty. The present results are compared with previous calculations and available measurements.
We compute the sphaleron rate of $N_f=2+1$ QCD at the physical point for a range of temperatures $200$ MeV $\lesssim T \lesssim 600$ MeV. We adopt a strategy recently applied in the quenched case, based on the extraction of the rate via a modified version of the Backus-Gilbert method from finite-lattice-spacing and finite-smoothing-radius Euclidean topological charge density correlators. The physical sphaleron rate is finally computed by performing a continuum limit at fixed physical smoothing radius, followed by a zero-smoothing extrapolation. Dynamical fermions were discretized using the staggered formulation, which is known to yield large lattice artifacts for the topological susceptibility. However, we find them to be rather mild for the sphaleron rate.
Light (sub-GeV) dark matter has gained increasing interest in terms of direct detection. Accelerated dark matter is a promising candidate that can generate detectable nuclear recoil energy within the sub-GeV range. Because of the large kinetic energy, its interactions with the nucleus are predominantly governed by inelastic scattering, including quasi-elastic and deep inelastic scattering. In this work, we calculated the inelastic effects in dark matter--Earth scattering mediated by a vector particle. Our analysis revealed that the impact of inelastic scattering relies on the mediator mass and the kinetic energy spectrum of dark matter. The results exhibited considerable disparity: the upper bounds of the exclusion limit for the spin-independent cross-section between accelerated dark matter and nuclei via a heavy mediator differ by several tens of times when inelastic scattering is considered.
The observation of neutrinoless double-beta ($0\nu\beta\beta$) decay would offer proof of lepton number violation, demonstrating that neutrinos are Majorana particles, while also helping us understand why there is more matter than antimatter in the Universe. If the decay is driven by the exchange of the three known light neutrinos, a discovery would, in addition, link the observed decay rate to the neutrino mass scale through a theoretical quantity known as the nuclear matrix element (NME). Accurate values of the NMEs for all nuclei considered for use in $0\nu\beta\beta$ experiments are therefore crucial for designing and interpreting those experiments. Here, we report the first comprehensive ab initio uncertainty quantification of the $0\nu\beta\beta$-decay NME, in the key nucleus $^{76}$Ge. Our method employs nuclear strong and weak interactions derived within chiral effective field theory and recently developed many-body emulators. Our result, with a conservative treatment of uncertainty, is an NME of $2.60^{+1.28}_{-1.36}$, which, together with the best-existing half-life sensitivity and phase-space factor, sets an upper limit for effective neutrino mass of $187^{+205}_{-62}$ meV. The result is important for designing next-generation germanium detectors aiming to cover the entire inverted hierarchy region of neutrino masses.
New GeV-scale dark forces coupling predominantly to quarks offer novel signatures that can be produced directly and searched for at high-luminosity colliders. We compute the photon-proton and electron-proton cross sections for producing a GeV-scale gauge boson arising from a $U(1)_B$ gauge symmetry. Our calculation relies on vector meson dominance and a phenomenological model for diffractive scattering used for vector-meson photoproduction. The parameters of our phenomenological model are fixed by performing a Markov Chain Monte Carlo fit to existing exclusive photoproduction data for $\omega$ and $\phi$ mesons. Our approach can be generalized to other GeV-scale dark gauge forces.
Recent BESIII data on radiative $J/\psi$ decays from $\sim 10^{10}$ $J/\psi$ samples should significantly advance our understanding of the controversial nature of $\eta(1405/1475)$. This motivates us to develop a three-body unitary coupled-channel model for radiative $J/\psi$ decays to three-meson final states of any partial wave ($J^{PC}$). Basic building blocks of the model are bare resonance states such as $\eta(1405/1475)$ and $f_1(1420)$, and $\pi K$, $K\bar{K}$, and $\pi\eta$ two-body interactions that generate resonances such as $K^*(892)$, $K^*_0(700)$, and $a_0(980)$. This model reasonably fits $K_SK_S\pi^0$ Dalitz plot pseudo data generated from the BESIII's $J^{PC}=0^{-+}$ amplitude for $J/\psi\to\gamma K_SK_S\pi^0$. The experimental branching ratios of $\eta(1405/1475)\to\eta\pi\pi$ and $\eta(1405/1475)\to\gamma\rho$ relative to that of $\eta(1405/1475)\to K\bar{K}\pi$ are simultaneously fitted. Our $0^{-+}$ amplitude is analytically continued to find three poles, two of which correspond to $\eta(1405)$ on different Riemann sheets of the $K^*\bar{K}$ channel, and the third one for $\eta(1475)$. This is the first pole determination of $\eta(1405/1475)$ and, furthermore, the first-ever pole determination from analyzing experimental Dalitz plot distributions with a manifestly three-body unitary coupled-channel framework. Process-dependent $\eta\pi\pi$, $\gamma\pi^+\pi^-$, and $\pi\pi\pi$ lineshapes of $J/\psi\to\gamma(0^{-+})\to \gamma(\eta\pi\pi)$, $\gamma(\gamma\rho)$, and $\gamma(\pi\pi\pi)$ are predicted, and are in reasonable agreement with data. A triangle singularity is shown to play a crucial role to cause the large isospin violation of $J/\psi\to\gamma(\pi\pi\pi)$.
We discuss the analytic continuation of scaling function in the 3-dimensional Z(2),O(2) andO(4) universality classes using the Schofield representation of the magnetic equation of state. We show that a determination of the location of Lee-Yang edge singularities and, in the case of Z(2), also the Langer edge singularity yields stable results. Results for the former are in good agreement with Functional Renormalization Group calculations. We also present results for the location of the Langer edge singularity in the 3-d,Z(2) universality class. We find that in terms of the complex scaling variable z the distance of the Langer edge singularity to the critical point agrees within errors with that of the Lee-Yang edge singularity. Furthermore the magnitude of the discontinuity along the Langer branch cut is an order of magnitude smaller than that along the Lee-Yang branch cut.
Radiative decays $D^*_{(s)}\to D_{(s)}\gamma$ are revisited in light of new experimental data from the \textit{BABAR} and BESIII collaborations. The radiative couplings $g_{D^*D\gamma}$ encoding nonperturbative QCD effects are calculated in the framework of the covariant confined quark model developed by us. We compare our results with other theoretical studies and experimental data. The couplings (in $\textrm{GeV}^{-1}$) $|g_{D^{*+}D^+\gamma}| = 0.45(9)$ and $|g_{D^{*0}D^0\gamma}| = 1.72(34)$ calculated in our model agree with the corresponding experimental data $|g_{D^{*+}D^+\gamma}|=0.47(7)$ and $|g_{D^{*0}D^0\gamma}|=1.77(16)$. The most interesting case is the decay $D^*_s\to D_s\gamma$, for which a recent prediction based on light-cone sum rules at next-to-leading order $|g_{D^*_s D_s\gamma}|=0.60(19)$ deviates from the first (and only to date) lattice QCD result $|g_{D^*_s D_s\gamma}|=0.11(2)$ at nearly $3\sigma$. Our calculation yields $|g_{D^*_s D_s\gamma}|=0.29(6)$, which falls somehow between the two mentioned results, although it is larger than those predicted in other studies using quark models or QCD sum rules.
In the wake of the first-ever experimental study of the decay: $D_s^{*+}\to e^+\nu_e$ with $e^+e^-$ collision data taken from the BESIII detector at the BEPCII collider, we study the purely leptonic decay of the charged vector mesons ($D^*_{(s)}$) in the framework of the relativistic independent quark (RIQ) model based on an average flavor-independent confining potential in equally mixed scalar-vector harmonic form. We calculate the decay constants: $f_{D^*}$ and $f_{D_s^*}$ representing the decay amplitudes using the meson wave function derivable in the RIQ model. Our results for the decay constants: $f_{D^*}=197\pm 14$ MeV, $f_{D_s^*}=236\pm 19$ MeV, decay widths: $\Gamma (D^*\to e\nu_e)=(57.523\pm 8.183) \ \mu eV$, $\Gamma (D_s^*\to e\nu_e) = (1.802\pm 0.275) \ meV$ and corresponding branching fractions (BFs): ${\cal B} (D^*\to e\nu_e)= (6.897\pm 0.992)\times 10^{-10}$ and ${\cal B} (D_s^*\to e\nu_e)= (2.574\pm 1.102) \times 10^{-5}$ are in good agreement with available experimental data and other model predictions including those from the lattice QCD calculation. Our predictions: ${\cal R}_{D^{*+}}=0.0665$ and ${\cal R}_{D_s^{*+}}=0.1157$, which correspond to the ratios of the BFs for $D_{(s)}^{*+}$ decays in their $\tau^-$ mode to the corresponding values in $e^-$ mode, are in good agreement with the results of the LQCD and LFQM calculations.
We explore the properties of neutral mesons within the context of a chirally imbalanced medium, employing the two-flavor Nambu--Jona-Lasinio model. The temperature dependence of the constituent quark mass at finite values of the chiral chemical potential (CCP) demonstrates the well-established phenomena of chiral catalysis at lower temperatures and inverse chiral catalysis at higher temperatures. The polarization functions in both the scalar ($\sigma$) and pseudo-scalar ($\pi^0$) channels have been evaluated using real time formalism of thermal field theory. These have been used to determine the masses and spectral functions of $ \sigma $ and $ \pi $ mesons. Detailed investigation of the analytic structure of the imaginary part of the polarization function for $\sigma$ and $\pi$ mesons results in the emergence of non-trivial Landau cut contributions due to the presence of chiral imbalance. The multiple solutions for the mass of the $\pi$ meson for specific values of CCP have been analysed on the basis of their residue at the pole. Furthermore, we have observed abrupt changes in the masses of both scalar and pseudo-scalar mesons at finite CCP values, particularly at higher temperatures. A decreasing trend in the Mott transition temperature is seen with the increase in CCP.
It is known that two heavy Majorana right-handed neutrinos are sufficient to generate the baryon asymmetry in the present universe. Thus, it is interesting to identify the third right-handed neutrino $N$ with the dark matter. We impose a new discrete symmetry $Z_2$ on this dark matter neutrino to stabilize it. However, the $U(1)_{B-L}$ gauge boson $A'$ couples to the right-handed neutrino $N$. If the $B-L$ breaking scale $V_{B-L}$ is sufficiently low, the dark matter neutrino $N$ can be in the thermal bath. We find that the thermal relic $N$ can explain the dark matter abundance for the $B-L$ breaking scale $ V_{B-L} \sim O(10)\,$TeV. After considering all the constraints from the existing experiments, a narrow mass region of the thermal produced right-handed neutrino dark matter $N$ is still surviving.
We show that the propagator derived from an EFT incorporating Weinbeger's compositeness theorem is the more general formula to describe the S-wave near threshold states. Using the propagator to fit the lineshape, one can extract $Z$ for these states and clarify the structure of these states.
We investigate the effects of boost invariance breaking on the isotropization of pressure in the glasma, using the $3+1$D glasma simulation. The breaking is attributed to spatial fluctuations of the classical color charge density along the collision axis. We present numerical results for pressure and energy density at mid-rapidity and across a wider rapidity region. It is found that, despite varying longitudinal correlation lengths, the behaviors of the pressure isotropizations are qualitatively similar. The numerical results suggest that, in the initial stage, longitudinal color electromagnetic fields develop, similar to those in the boost invariant glasma. Subsequently, these fields evolve into a dilute glasma, expanding longitudinally in a manner akin to a dilute gas. We also show that the energy density at mid-rapidity exhibits a $1/\tau$ decay in the dilute glasma stage.
Virtually all high-energy-physics (HEP) simulations for the LHC rely on Monte Carlo using importance sampling by means of the VEGAS algorithm. However, complex high-precision calculations have become a challenge for the standard toolbox. As a result, there has been keen interest in HEP for modern machine learning to power adaptive sampling. Despite previous work proving that normalizing-flow-powered neural importance sampling (NIS) sometimes outperforms VEGAS, existing research has still left major questions open, which we intend to solve by introducing Z\"uNIS, a fully automated NIS library. We first show how to extend the original formulation of NIS to reuse samples over multiple gradient steps, yielding a significant improvement for slow functions. We then benchmark Z\"uNIS over a range of problems and show high performance with limited fine-tuning. The library can be used by non-experts with minimal effort, which is crucial to become a mature tool for the wider HEP public.
We have studied the mass spectra of doubly charmed pentaquark states in the $\Lambda _{c}^{(*)}D^{(*)}$ and $\Sigma _{c}^{(*)}D^{(*)}$ channels with $J^P=1/2^\pm$, $3/2^\pm$ and $5/2^\pm$ within the framework of QCD sum rules. We use the parity projected sum rules to separate the contributions of negative and positive parities from the two-point correlations induced by the pentaquark interpolating currents. Our results show that the bound states of $P_{cc}$ pentaquarks may exist in the $\Lambda _cD\, (\frac{1}{2}^-)$, $\Sigma _cD\, (\frac{1}{2}^-)$, $\Sigma _cD^*\, (\frac{3}{2}^-)$, $\Lambda _c^*D\, (\frac{3}{2}^-)$, $\Lambda _c^*D^*\, (\frac{5}{2}^-)$ channels with negative-parity and $\Sigma _cD\, (\frac{1}{2}^+)$, $\Sigma _cD^\ast\, (\frac{3}{2}^+)$, $\Sigma _c^\ast D\, (\frac{3}{2}^+)$ channels with positive-parity, since their masses are predicted to be lower than the corresponding meson-baryon thresholds. However, they are still allowed to decay into the $\Xi_{cc}^{(\ast)}\pi$ final states via strong interaction. The triply charged $P_{cc}^{+++}(ccuu\bar d)$ and neutral $P_{cc}^{0}(ccdd\bar u)$ in the isospin quartet would definitely be pentaquark states due to their exotic charges. We suggest searching for these characteristic doubly charmed pentaquark signals in the $P_{cc}^{+++}\to\Xi_{cc}^{(\ast) ++}\pi^+/\rho^+$, $\Sigma_c^{(\ast)++}D^{(\ast)+}$ and $P_{cc}^{0}\to\Xi_{cc}^{(\ast) +}\pi^-/\rho^-$, $\Sigma_c^{(\ast)0}D^{(\ast)0}$ decays in the near future.
We study the potential of $X(3872)$ at finite temperature in the Born-Oppenheimer approximation under the assumption that it is a tetraquark. We argue that, at large number of colors, it is a good approximation to assume that the potential consists in a real part plus a constant imaginary term. The real part is then computed adapting an approach by Rothkopf and Lafferty and using as input lattice QCD determinations of the potential for hybrids. This model allows us to qualitatively estimate at which temperature range the formation of a heavy tetraquark is possible, and to propose a qualitative picture for the dissociation of the state in a medium. Our approach can be applied to other suggested internal structures for the $X(3872)$ and to other exotic states.
We use equivariant localization to construct off-shell entropy functions for supersymmetric black holes in $\mathcal{N}=2$, $D=4$ gauged supergravity coupled to matter. This allows one to compute the black hole entropy without solving the supergravity equations of motion and provides a novel generalization of the attractor mechanism. We consider magnetically charged black holes in $AdS_4$ which have an $AdS_2\times M_2$ near horizon geometry, where $M_2$ is a sphere or a spindle, and we also obtain entropy functions for ungauged supergravity as a simple corollary. We derive analogous results for black strings and rings in $D=5$ supergravity which have an $AdS_3\times M_2$ near horizon geometry, and in this setting we derive an off-shell expression for the central charge of the dual $\mathcal{N}=(0,2)$, $d=2$~SCFT.
We advance the multipoint lightcone bootstrap and compute anomalous dimensions of triple-twist operators at large spin. In contrast to the well-studied double-twist operators, triple-twist primaries are highly degenerate so that their anomalous dimension is encoded in a matrix. At large spin, the degeneracy becomes infinite and the matrix becomes an integral operator. We compute this integral operator by studying a particular non-planar crossing equation for six-point functions of scalar operators in a lightcone limit. The bootstrap analysis is based on new formulas for six-point lightcone blocks in the comb-channel. For a consistency check of our results, we compare them to perturbative computations in the epsilon expansion of $\phi^3$ and $\phi^4$ theory. In both cases, we find perfect agreement between perturbative results and bootstrap predictions. As a byproduct of our studies, we extend earlier work of Derkachov and Manashov to compute the anomalous dimension matrices of all triple-twist primaries in scalar $\phi^3$ and $\phi^4$ theory to first and second order in epsilon, respectively.
In the Euclidean-space formulation of integral equations for the structure of quantum chromodynamics (QCD) bound states, the quark propagators with complex-valued momentum are densely sampled. We therefore propose an accurate and efficient algorithm to compute these propagators. The quark propagator both on the spacelike real axis and at complex-valued momenta is determined from its Schwinger-Dyson equation (SDE). We first apply an iterative solver to determine the quark propagator on the spacelike real axis. The propagator at complex-valued momenta is then computed from its self-energy based on this solution, where demanding integrals are encountered. In order to compute of these integrals, we apply customized variable transformations for the radial integral after subtracting the asymptotics. We subsequently apply an optional compound of quadrature rules for the angular integral. The contribution from the asymptotics is added at the last step. The accuracy and the performance of this algorithm for the quark propagator at complex-valued momentum are tested in comparison with an adaptive quadrature.
It has been shown that by using a Lagrange multiplier field to ensure that the classical equations of motion are satisfied, radiative effects beyond one-loop order are eliminated. It has also been shown that through the contribution of some additional ghost fields, the effective action becomes form invariant under a redefinition of field variables, and furthermore, the usual one-loop results coincide with the quantum corrections obtained from this effective action. In this paper, we consider the consequences of a gauge invariance being present in the classical action. The resulting gauge transformations for the Lagrange multiplier field as well as for the additional ghost fields are found. These gauge transformations result in a set of Faddeev-Popov ghost fields arising in the effective action. If the gauge algebra is closed, we find the Becci-Rouet-Stora-Tyutin (BRST) transformations that leave the effective action invariant.
Vacuum polarization (VP) is investigated for the interaction of a polarized $\gamma$-ray beam of GeV photons with a counterpropagating ultraintense laser pulse. In a conventional setup of a vacuum birefringence measurement, a VP signal is the emerging small circular (linear) polarization of the initially linearly (circularly) polarized probe photons. The pair production via the nonlinear Breit-Wheeler process in such a high-energy environment eliminates part of the $\gamma$-photons in the outgoing $\gamma$-beam, increasing the statistical error and decreasing the accuracy of this VP signal. In contrast, we investigate the conversion of the emerging circular polarization of $\gamma$-photons into longitudinal polarization of the created positrons, considering the latter as the main VP signal. To study the VP effects in the highly nonlinear regime, where the Euler-Heisenberg effective Lagrangian method breaks down, we have developed a Monte-Carlo simulation method, incorporating vacuum birefringence and dichroism via the one-loop QED probabilities in the locally constant field approximation. Our Monte Carlo method will enable the study of VP effects in strong fields of arbitrary configuration. With 10~PW laser systems, we demonstrate the feasibility of detecting the fermionic signal of the VP effect at the 5$\sigma$ confidence level with a few hours of measurement time.
We propose a holographic dictionary which comes from reducing the bulk theories in an asymptotically flat spacetime to its null infinity. A general boundary theory is characterized by a fundamental field, an infinite tower of descendant fields, constraints among the fundamental field and its descendants as well as a symplectic form. For the Carrollian diffeomorphisms, we can construct the corresponding Hamiltonians which are also the fluxes from the bulk, and whose quantum operators realize this algebra with a divergent central charge. This central charge reflects the propagating degrees of freedom and can be regularized. For the spinning theory, we need a helicity flux operator to close the algebra which relates to the duality transformation.
The topological magnetoelectric effect (TME) is a unique macroscopic manifestation of quantum states of matter possessing topological order and it is described by axion electrodynamics. In three-dimensional topological insulators, for instance, the axion coupling is of the order of the fine structure constant, and hence a perturbative analysis of the field equations is plenty justified. In this paper we use Green's function techniques to obtain time-dependent solutions to the axion field equations in the presence of a planar domain-wall separating two media with different topological order. We apply our results to investigate the radiation of a short linear antenna near the domain-wall.
The SU($N$) principal chiral model is asymptotically free and integrable in $1+1$ dimensions. In the large-$N$ limit, there is no scattering, but correlation functions are {\em not} those of a free field theory. We briefly review the derivation of form factors for local operators. Two-point functions for such operators are known exactly. The two-point function of scaling-field operators has the short-distance behavior expected from the renormalization group. We briefly discuss non-vacuum operator products. The ultimate goal is to derive the Lagrangian field theory from this axiomatic quantum-field-theory formalism.
Conformal field theories can exchange energy through a boundary interface. Imposing conformal boundary conditions for static interfaces implies energy conservation at the interface. Recently, the reflective and transmitive properties of such static conformal interfaces have been studied in two dimensions by scattering matter at the interface impurity. In this note, we generalize this to the case of dynamic interfaces. Motivated by the connections between the moving mirror and the black hole, we choose a particular profile for the dynamical interface. We show that a part of the total energy of each side will be lost in the interface. In other words, a time-dependent interface can accumulate or absorb energy. While, in general, the interface follows a time-like trajectory, one can take a particular limit of a profile parameter($\beta$), such that the interface approaches a null line asymptotically$(\beta\rightarrow 0)$. In this limit, we show that for a class of boundary conditions, the interface behaves like a `semipermeable membrane'. We also consider another set of conformal boundary conditions for which, in the null line limit, the interface mimics the properties expected of a horizon. In this case, we devise a scattering experiment, where (zero-point subtracted) energy from one CFT is fully transmitted to the other CFT, while from the other CFT, energy can neither be transmitted nor reflected, i.e., it gets lost in the interface. This boundary condition is also responsible for the thermal energy spectrum which mimics Hawking radiation. This is analogous to the black hole where the horizon plays the role of a one-sided `membrane', which accumulates all the interior degrees of freedom and radiates thermally in the presence of quantum fluctuation. Stimulated by this observation, we comment on some plausible construction of wormhole analogues.
We find new bilinear relations for the partition functions of U(N)_k x U(N+M)_{-k} ABJ theory with two parameter mass deformation (m_1,m_2), which generalize the q-Toda-like equation found previously for m_1=m_2. By combining the bilinear relations with the Seiberg-like dualities and the duality cascade relations, we can determine the exact values of the partition functions recursively with respect to N. This method is more efficient than the exact calculation by the standard TBA-like approach in the Fermi gas formalism. As an application we study the large N asymptotics of the partition function with the mass parameters in the supercritical regime where the large N expansion obtained for small mass parameters is invalid.
Calabi-Yau links are specific $S^1$-fibrations over Calabi-Yau manifolds, when the link is 7-dimensional they exhibit both Sasakian and G2 structures. In this invited contribution to the DANGER proceedings, previous work exhaustively computing Calabi-Yau links and selected topological properties is summarised. Machine learning of these properties inspires new conjectures about their computation, as well as the respective Gr\"obner bases.
The differential scattering cross section for the problem of fast charged particles motion near a flat relativistic beam of charged particles was obtained. The problem is considered in the eikonal approximation in the representation of the beam by a continuous potential.
In this article we briefly survey some developments in gauged linear sigma models (GLSMs). Specifically, we give an overview of progress on constructions of GLSMs for various geometries, GLSM-based computations of quantum cohomology, quantum sheaf cohomology, and quantum K theory rings, as well as two-dimensional abelian and non-abelian mirror constructions. (Contribution to the proceedings of Gauged Linear Sigma Models@30 (Simons Center, Stony Brook, May 2023).)
A lattice QCD calculation for the four gluon one-particle irreducible Green function in the Landau gauge is discussed. Results for some of the associated form factors are reported for kinematical configurations with a single momentum scale. Our results show that the computation of this Green function requires large statistical ensembles with 10K or larger number of gauge configurations. The simulations considered herein have a clear Monte Carlo signal for momenta up to $\sim 1$ GeV. The form factors show an hierarchy, with the form factor associated with the tree level Feynman rule being dominant and essentially constant for the range of momenta accessed. The remaining form factors seem to increase as the momentum decreases, suggesting that a possible $\log$ divergence may occur. The computed form factors are, at least, in qualitative agreement with the results obtained with continuum approaches to this vertex, when available.
Black hole information problem is the question about unitarity of the evolution operator during the collapse and evaporation of the black hole. One can ask the same question about unitarity of quantum and inflationary cosmology. In this paper we argue that in both cases, for black holes and for cosmology, the answer is negative and we face non-unitarity. Such a question can not be addressed by using the fixed classical gravitational background since one has to take into account the backreaction. To his end one uses the semi-classical gravity, which includes the expectation value of the energy - momentum tensor operator of the matter fields. One has to renormalize the energy-momentum tensor and one gets an effective action which contains quadratic terms in scalar curvature and Ricci tensor. Such quadratic gravity contains ghosts which in fact lead to violation of unitarity in black holes and cosmology. We discuss the question whether black holes will emit ghosts. One can try to restrict ourselves to the $f(R)$ gravity that seems is a good approximation to the semi-classical gravity and widely used in cosmology. The black hole entropy in $f(R)$ gravity is different from the Bekenstein-Hawking entropy and from entanglement island entropy. The black hole entropy in $R+R^2$ gravity goes to a constant during the evaporation process. This can be interpreted as another indication to the possible non-unitarity in black holes and cosmology
We investigate gap-closings in one- and two-dimensional tight-binding models with two bands, containing non-Hermitian hopping terms, and open boundary conditions (OBCs) imposed along one direction. We compare the bulk OBC spectra with the periodic boundary condition (PBC) spectra, pointing out that they do not coincide, which is an intrinsic characteristic of non-Hermitian systems. The non-Hermiticity thus results in the failure of the familiar notions of bulk-boundary correspondence found for Hermitian systems. This necessitates the search for topological invariants which can characterize gap-closings in open non-Hermitian systems correctly and unambiguously. We elucidate the behaviour of two possible candidates applicable for one-dimensional slices -- (1) the sum of winding numbers for the two bands defined on a generalized Brillouin zone and (2) the biorthogonal polarization (BP). While the former shows jumps/discontinuities for some of the non-Hermitian systems studied here, at points when an edge mode enters the bulk states and becomes delocalized, it does not maintain quantized values in a given topological phase. On the contrary, BP shows jumps and at phase transitions takes the quantized value of one or zero, which corresponds to whether an actual edge mode exists or whether that mode is delocalized and absorbed within the bulk (not being an edge mode anymore).
Consider the $3$-dimensional $\mathcal N=4$ supersymmetric gauge theory associated with a compact Lie group $G_c$ and its quaternionic representation $\mathbf M$. Physicists study its Coulomb branch, which is a noncompact hyper-K\"ahler manifold with an $\mathrm{SU}(2)$-action, possibly with singularities. We give a mathematical definition of the Coulomb branch as an affine algebraic variety with $\mathbb C^\times$-action when $\mathbf M$ is of a form $\mathbf N\oplus\mathbf N^*$, as the second step of the proposal given in arXiv:1503.03676.
This is the second companion paper of arXiv:1601.03586. We consider the morphism from the variety of triples introduced in arXiv:1601.03586 to the affine Grassmannian. The direct image of the dualizing complex is a ring object in the equivariant derived category on the affine Grassmannian (equivariant derived Satake category). We show that various constructions in arXiv:1601.03586 work for an arbitrary commutative ring object. The second purpose of this paper is to study Coulomb branches associated with star shaped quivers, which are expected to be conjectural Higgs branches of $3d$ Sicilian theories in type $A$ by arXiv:1007.0992.
We propose a new framework for simulating $\text{U}(k)$ Yang-Mills theory on a universal quantum computer. This construction uses the orbifold lattice formulation proposed by Kaplan, Katz, and Unsal, who originally applied it to supersymmetric gauge theories. Our proposed approach yields a novel perspective on quantum simulation of quantum field theories, carrying certain advantages over the usual Kogut-Susskind formulation. We discuss the application of our constructions to computing static properties and real-time dynamics of Yang-Mills theories, from glueball measurements to AdS/CFT, making use of a variety of quantum information techniques including qubitization, quantum signal processing, Jordan-Lee-Preskill bounds, and shadow tomography. The generalizations to certain supersymmetric Yang-Mills theories appear to be straightforward, providing a path towards the quantum simulation of quantum gravity via holographic duality.
We study the $n$-point differentials corresponding to Kadomtsev-Petviashvili tau functions of hypergeometric type (also known as Orlov-Scherbin partition functions), with an emphasis on their $\hbar^2$-deformations and expansions. Under the naturally required analytic assumptions, we prove certain higher loop equations that, in particular, contain the standard linear and quadratic loop equations, and thus imply the blobbed topological recursion. We also distinguish two large families of the Orlov-Scherbin partition functions that do satisfy the natural analytic assumptions, and for these families we prove in addition the so-called projection property and thus the full statement of the Chekhov-Eynard-Orantin topological recursion. A particular feature of our argument is that it clarifies completely the role of $\hbar^2$-deformations of the Orlov-Scherbin parameters for the partition functions, whose necessity was known from a variety of earlier obtained results in this direction but never properly understood in the context of topological recursion. As special cases of the results of this paper one recovers new and uniform proofs of the topological recursion to all previously studied cases of enumerative problems related to weighted double Hurwitz numbers. By virtue of topological recursion and the Grothendieck-Riemann-Roch formula this, in turn, gives new and uniform proofs of almost all ELSV-type formulas discussed in the literature.
We describe a new method for constraining Laplacian spectra of hyperbolic surfaces and 2-orbifolds. The main ingredient is consistency of the spectral decomposition of integrals of products of four automorphic forms. Using a combination of representation theory of $\mathrm{PSL}_2(\mathbb{R})$ and semi-definite programming, the method yields rigorous upper bounds on the Laplacian spectral gap. In several examples, the bound is nearly sharp. For instance, our bound on all genus-2 surfaces is $\lambda_1\leq 3.8388976481$, while the Bolza surface has $\lambda_1\approx 3.838887258$. The bounds also allow us to determine the set of spectral gaps attained by all hyperbolic 2-orbifolds. Our methods can be generalized to higher-dimensional hyperbolic manifolds and to yield stronger bounds in the two-dimensional case. The ideas were closely inspired by modern conformal bootstrap.
We combine histogram reweighting techniques with the two-lattice matching Monte Carlo renormalization group method to conduct computationally efficient calculations of critical exponents on systems with moderately small lattice sizes. The approach, which relies on the construction of renormalization group mappings between two systems of identical lattice size to partially eliminate finite-size effects, and the use of histogram reweighting to obtain computationally efficient results in extended regions of parameter space, is utilized to explicitly determine the renormalized coupling parameters of the two-dimensional $\phi^{4}$ scalar field theory and to extract multiple critical exponents. We conclude by quantifying the computational benefits of the approach and discuss how reweighting opens up the opportunity to extend Monte Carlo renormalization group methods to systems with complex-valued actions.
We discuss the dynamics of integrable and nonintegrable chains of coupled oscillators under continuous weak position measurements in the semiclassical limit. We show that, in this limit, the dynamics is described by a standard stochastic Langevin equation, and a measurement-induced transition appears as a noise- and dissipation-induced chaotic-to-nonchaotic transition akin to stochastic synchronization. In the nonintegrable chain of anharmonically coupled oscillators, we show that the temporal growth and the ballistic light-cone spread of a classical out-of-time correlator characterized by the Lyapunov exponent and the butterfly velocity, are halted above a noise or below an interaction strength. The Lyapunov exponent and the butterfly velocity both act like order parameter, vanishing in the nonchaotic phase. In addition, the butterfly velocity exhibits a critical finite-size scaling. For the integrable model, we consider the classical Toda chain and show that the Lyapunov exponent changes nonmonotonically with the noise strength, vanishing at the zero noise limit and above a critical noise, with a maximum at an intermediate noise strength. The butterfly velocity in the Toda chain shows a singular behavior approaching the integrable limit of zero noise strength.
In this work we derive braid group representations and Stokes matrices for Liouville conformal blocks with one irregular operator. By employing the Coulomb gas formalism, the corresponding conformal blocks can be interpreted as wavefunctions of a Landau-Ginzburg model specified by a superpotential $\mathcal{W}$. Alternatively, these can also be viewed as wavefunctions of a 3d TQFT on a 3-ball with boundary a 2-sphere on which the operator insertions represent Anyons whose fusion rules describe novel topological phases of matter.
Bethe ansatz equations for spin-$s$ Heisenberg spin chain with $s\ge1$ are significantly more difficult to analyze than the spin-$\tfrac{1}{2}$ case, due to the presence of repeated roots. As a result, it is challenging to derive extra conditions for the Bethe roots to be physical and study the related completeness problem. In this paper, we propose the rational $Q$-system for the XXX$_s$ spin chain. Solutions of the proposed $Q$-system give all and only physical solutions of the Bethe ansatz equations required by completeness. This is checked numerically and proved rigorously. The rational $Q$-system is equivalent to the requirement that the solution and the corresponding dual solution of the $TQ$-relation are both polynomials, which we prove rigorously. Based on this analysis, we propose the extra conditions for solutions of the XXX$_s$ Bethe ansatz equations to be physical.
We develop a new method to calculate finite size corrections for form factors in two-dimensional integrable quantum field theories. We extract these corrections from the excited state expectation value of bilocal operators in the limit when the operators are far apart. We elaborate the finite size effects explicitly up to the 3rd L\"uscher order and conjecture the structure of the general form. We also fully recover the explicitly known massive fermion finite volume form factors.
It is shown that the $gl(3)$ polynomial integrable system introduced by Sokolov-Turbiner is equivalent to the $gl(3)$ quantum Euler-Arnold top in a constant magnetic field. Their Hamiltonian and their 3rd order Integral can be rewritten in terms of $gl(3)$ algebra generators. All $gl(3)$ generators can be represented by the non-linear elements of the universal enveloping algebra of the 5-dimensional Heisenberg algebra $h_5(\hat{p}_{1,2},\hat{q}_{1,2}, I)$. Four different representations of the $h_5$ Heisenberg algebra are used: (I) by differential operators in two real (complex) variables, (II) by finite-difference operators on uniform or exponential lattices. We discovered the existence of two 2-parametric bilinear and trilinear elements (denoted $H$ and $I$, respectively) of the universal enveloping algebra $U(gl(3))$ such that their Lie bracket (commutator) can be written as a linear superposition of {\it nine} so-called {\it artifacts} - the special bilinear elements of $U(gl(3))$, which vanish once the representation of the $gl(3)$-algebra generators is written in terms of the $h_5(\hat{p}_{1,2},\hat{q}_{1,2}, I)$-algebra generators. In this representation all nine artifacts vanish, two of the above-mentioned elements of $U(gl(3))$ commute(!). If $(\hat{p},\hat{q})$ are represented by finite-difference/discrete operators on uniform or exponential lattice, the Hamiltonian and the Integral of the 3-body elliptic Calogero model become the isospectral, finite-difference operators on uniform-uniform or exponential-exponential lattices (or mixed) with polynomial coefficients. If $(\hat{p},\hat{q})$ are written in complex $(z, \bar{z})$ variables the Hamiltonian corresponds to a complexification of the 3-body elliptic Calogero model on $C^2$.
We consider gluons scattering in Type IIB string theory on AdS$_5\times S^5/\mathbb{Z}_2$ in the presence of D7 branes, which is dual to the flavor multiplet correlator in a certain 4d $\mathcal{N}=2$ $USp(2N)$ gauge theory with $SO(8)$ flavor symmetry and complexified coupling $\tau$. We compute this holographic correlator in the large $N$ and finite $\tau$ expansion using constraints from derivatives of the mass deformed sphere free energy, which we compute to all orders in $1/N$ and finite $\tau$ using supersymmetric localization. In particular, we fix the $F^4$ higher derivative correction to gluon scattering on AdS at finite string coupling $\tau_s=\tau$ in terms of Jacobi theta functions, which feature the expected relations between the $SL(2,\mathbb{Z})$ duality and the $SO(8)$ triality of the CFT, and match it to the known flat space term. We also use the flat space limit to compute $D^2F^4$ corrections of the correlator at finite $\tau$ in terms of a non-holomorphic Eisenstein series. At weak string coupling, we find that the AdS correlator takes a form which is remarkably similar to that of the flat space Veneziano amplitude.
The correlation function in quantum systems plays a vital role in decoding their properties and gaining insights into physical phenomena. Its interpretation corresponds to the propagation of particle excitations between spacetime, sharing a similar spirit to the idea of quantum weak measurement in terms of recording the system information by interaction. By defining Weak-Valued Correlation Function, we propose the basic insights and the universal methods for recording them on the apparatus through weak measurement. To demonstrate the feasibility of our approach, we perform numerical experiments of perturbed quantum harmonic oscillators, addressing the intricate interplay between the coupling strength and the number of ensemble copies. Additionally, we extend our protocol to the domain of quantum field theory, where joint weak values encode crucial information about the correlation function. Hopefully, this comprehensive investigation could advances our understanding of the fundamental nature of correlation function and weak measurement in quantum theories.
In this paper, we shall study the phase transition of non-minimal coupling of Einstein-Hilbert gravity and electric field of Yang-Mills type in AdS space-time. We couple the Ricci scalar to the Yang-Mills invariant to obtain a modified theory of gravity. A black brane solution is introduced up to the first order of the term $RF^{(a)}_{\mu \alpha }F^{(a)\mu \alpha} $ in this model. Then, the phase transition of this solution will be investigated in canonical ensemble. Our investigation shows that only the second order phase transition behavior is seen in this model. Also, due to the coupling of the Yang-Mills field and Ricci scalar, there are differences with the phase transitions of the usual minimal models. We shall show that in the absence of non-minimal coupling there is no any phase transition.
We calculate the $T\bar{T}$-deformed entanglement entropy for integrable quantum field theories (IQFTs) using the form factor bootstrap approach. We solve the form factor bootstrap axioms for the branch-point twist fields and obtain the deformed form factors. Using these form factors, we compute the deformed von Neuman entropy up to two particle contributions. The solution of the form factor axioms is not unique. We find that for the simplest solution of the bootstrap axioms, the UV limit of the entanglement entropy takes the same form as the undeformed one, but the effective central charge is deformed. For solutions with additional CDD-like factors, we can have different behaviors. The IR corrections, which only depends on the particle spectrum is untouched.
We introduce manifestly crossing-symmetric expansions for arbitrary systems of 1D CFT correlators. These expansions are given in terms of certain Polyakov blocks which we define and show how to compute efficiently. Equality of OPE and Polyakov block expansions leads to sets of sum rules that any mixed correlator system must satisfy. The sum rules are diagonalized by correlators in tensor product theories of generalized free fields. We show that it is possible to do a change of a basis that diagonalizes instead mixed correlator systems involving elementary and composite operators in a single field theory. As an example, we find the first non-trivial examples of optimal bounds, saturated by the mixed correlator system $\phi,\phi^2$ in the theory of a single generalized free field.
We induce and study a topological dynamical phase transition between two planar superconducting phases. Using the Lindblad equation to account for the interactions of Bogoliubov quasiparticles among themselves and with the fluctuations of the superconducting order parameter, we derive the relaxation dynamics of the order parameter. To characterize the phase transition, we compute the fidelity and the spin-Hall conductance of the open system. Our approach provides crucial informations for experimental implementations, such as the dependence of the critical time on the system-bath coupling.
We explain how equivariant localization may be applied to AdS/CFT to compute various BPS observables in gravity, such as central charges and conformal dimensions of chiral primary operators, without solving the supergravity equations. The key ingredient is that supersymmetric AdS solutions with an R-symmetry are equipped with a set of equivariantly closed forms. These may in turn be used to impose flux quantization and compute observables for supergravity solutions, using only topological information and the Berline--Vergne--Atiyah--Bott fixed point formula. We illustrate the formalism by considering $AdS_5\times M_6$ and $AdS_3\times M_8$ solutions of $D=11$ supergravity. As well as recovering results for many classes of well-known supergravity solutions, without using any knowledge of their explicit form, we also compute central charges for which explicit supergravity solutions have not been constructed.
Recent studies have highlighted the significant role of utilizing $O(1,1)$ symmetry in the circular reduction of effective actions to determine NS-NS couplings in the effective action of string theory. However, these calculations often result in residual terms as total derivatives that do not conform to $O(1,1)$ transformations. In this paper, we present explicit calculations at $\alpha'$ order, demonstrating the enforceability of this symmetry on effective Lagrangians to establish the parameters governing covariant couplings in any scheme. Notably, we discover the $O(1,1)$-invariant Lagrangians corresponding to the Metsaev-Tseytlin action and the Miessner action.
The four different kinds of currents are given by the multiple $(\beta,\gamma)$ and $(b,c)$ ghost systems with a multiple product of derivatives. We determine their complete algebra where the structure constants depend on the deformation parameter $\lambda$ appearing in the conformal weights of above fields nontrivially and depend on the generic spins $h_1$ and $h_2$ appearing on the left hand sides in the (anti)commutators. By taking the linear combinations of these currents, the ${\cal N}=4$ supersymmetric linear $W_{\infty}[\lambda]$ algebra (and its ${\cal N}=4$ superspace description) for generic $\lambda$ is obtained explicitly. Moreover, we determine the ${\cal N}=2$ supersymmetric linear $W_{\infty}[\lambda]$ algebra for arbitrary $\lambda$. As a by product, the $\lambda$ deformed bosonic $W_{1+\infty}[\lambda] \times W_{1+\infty}[\lambda+\frac{1}{2}]$ subalgebra (a generalization of Pope, Romans and Shen's work in $1990$) is obtained. The first factor is realized by $(b,c)$ fermionic fields while the second factor is realized by $(\beta,\gamma)$ bosonic fields. The degrees of the polynomials in $\lambda$ for the structure constants are given by $(h_1+h_2-2)$. Each $w_{1+\infty}$ algebra from the celestial holography is reproduced by taking the vanishing limit of other deformation prameter $q$ at $\lambda=0$ with the contractions of the currents.
Quantum loop and dimer models are archetypal examples of correlated systems with local constraints, whose generic solutions are difficult to obtain due to the lack of controlled methods to solve them in the thermodynamic limit. Yet, these solutions are of immediate relevance towards both statistical and quantum field theories, as well as the fast-growing experiments in Rydberg atom arrays and quantum moir\'e materials, where the interplay between correlation and local constraints gives rise to a plethora of novel phenomena. In a recent work[1], it was found via sweeping cluster quantum Monte Carlo (QMC) simulations and field theory analysis that the triangular lattice quantum loop model (QLM) hosts a rich ground state phase diagram with lattice nematic (LN), vison plaquette (VP) crystals, and the $\mathbb{Z}_2$ quantum spin liquid (QSL) close to the Rokhsar-Kivelson (RK) point. Here, we focus on the continuous quantum critical point separating the VP and QSL phases and demonstrate via both static and dynamic probes in QMC simulations that this transition is of the (2+1)d Cubic* universality, in which the fractionalized visons in QSL condense to give rise to the crystalline VP phase, while leaving their trace in the anomalously large anomalous dimension exponent and pronounced continua in the dimer and vison spectra compared with those at the conventional Cubic or O(3) quantum critical points.
We consider the correlator $\langle \mathcal{L} \mathcal{K} \tilde{ \mathcal{K}} \rangle $ of the Lagrange operator of $\mathcal{N}=4$ super Yang-Mills theory and two conjugate two-excitation operators in an $su(2)$ sector. We recover the planar one-loop anomalous dimension of the renormalised operators from this hexagon computation.
In this paper we consider classical and quantum versions of the critical long-range $O(N)$ model, for which we study finite-size and finite-temperature effects, respectively, at large $N$. First, we consider the classical (isotropic) model, which is conformally invariant at criticality, and we introduce one compact spatial direction. We show that the finite size dynamically induces an effective mass and we compute the one-point functions for bilinear primary operators with arbitrary spin and twist. Second, we study the quantum model, mapped to a Euclidean anisotropic field theory, local in Euclidean time and long-range in space, which we dub \emph{fractional Lifshitz field theory}. We show that this model admits a fixed point at zero temperature, where it displays anisotropic Lifshitz scaling, and show that at finite temperature a thermal mass is induced. We then compute the one-point functions for an infinite family of bilinear scaling operators. In both the classical and quantum model, we find that, as previously noted for the short-range $O(N)$ model in [arXiv:1802.10266], the large-$N$ two-point function contains information about the one-point functions, not only of the bilinear operators, but also of operators that appear in the operator product expansion of two fundamental fields only at subleading order in $1/N$, namely powers of the Hubbard-Stratonovich intermediate field.
In this note, we discuss bulk reconstruction of massless free fields in flat space from the highest-weight representation of boundary Carrollian conformal field theory (CCFT). We expand the bulk field as a sum of infinite descendants of a primary state defined in the boundary CCFT, and discuss the Lorentz invariant bulk-boundary propagator in detail for the BMS_3/CCFT_2 case. In our calculation, it is necessary to introduce a nonzero mass at the very beginning and take it to be vanishing at the end. The framework we proposed has potential to probe local bulk physics from the boundary CCFT.
We study one-parameter families of $U(1)^2$ preserving deformations relating pairs of toric quiver gauge theories on D-branes probing local toric (pseudo) del Pezzo surfaces. The superpotential deformations are defined by zig-zag paths in the brane tiling and are non-trivial in the chiral ring if the geometry has a non-isolated singularity. In the dual $(p,q)$ web, the deformation is realized as a Hanany-Witten move that reverses a semi-infinite fivebrane. We use these deformations to find RG flows between 4d $\mathcal{N}=1$ SCFTs on D3-branes probing local toric (pseudo) del Pezzo surfaces of the same degree, and briefly comment on the interpretation for BPS quivers of rank one 5d SCFTs on $S^1$.
We provide a first principles derivation of the supersymmetric Casimir energy of $\mathcal{N}=1$ SCFTs in four dimensions using the supercharge algebra on general conformal supergravity backgrounds that admit Killing spinors. The superconformal Ward identities imply that there exists a continuous family of conserved R-currents on supersymmetric backgrounds, as well as a continuous family of conserved currents for each conformal Killing vector. These continuous families interpolate between the consistent and covariant R-current and energy-momentum tensor. The resulting Casimir energy, therefore, depends on two continuous parameters corresponding to the choice of conserved currents used to define the energy and R-charge. This ambiguity is in addition to any possible scheme dependence due to local terms in the effective action. As an application, we evaluate the general expression for the supersymmetric Casimir energy we obtain on a family of backgrounds with the cylinder topology $\mathbb{R}\times S^3$ and admitting a single Majorana supercharge. Our result is a direct consequence of the supersymmetry algebra, yet it resembles more known expressions for the non-supersymmetric Casimir energy on such backgrounds and differs from the supersymmetric Casimir energy obtained from the zero temperature limit of supersymmetric partition functions. We defer a thorough analysis of the relation between these results to future work.
For a static time slice of AdS$_3$ we describe a particular class of minimal surfaces which form trivalent networks of geodesics. Through geometric arguments we provide evidence that these surfaces describe a measure of multipartite entanglement. By relating these surfaces to Ryu-Takayanagi surfaces it can be shown that this multipartite contribution is related to the angles of intersection of the bulk geodesics. A proposed boundary dual, the multi-entropy, generalizes replica trick calculations involving twist operators by considering monodromies with finite group symmetry beyond the cyclic group used for the computation of entanglement entropy. We make progress by providing explicit calculations of Renyi multi-entropy in two dimensional CFTs and geometric descriptions of the replica surfaces for several cases with low genus. We also explore aspects of the free fermion and free scalar CFTs. For the free fermion CFT we examine subtleties in the definition of the twist operators used for the calculation of Renyi multi-entropy. In particular the standard bosonization procedure used for the calculation of the usual entanglement entropy fails and a different treatment is required.
Gas Electron Multiplier (GEM) is one of the mostly used gaseous detectors in the High Energy Physics (HEP) experiments. GEMs are widely used as tracking devices due to their high-rate handling capability and good position resolution. An initiative is taken to study the stability in performance of the GEM chamber prototypes in the laboratory using external radiation for different Argon based gas mixtures. The effect of ambient parameters on the gain and energy resolution are studied. Very recently some behavioural changes in the performance of a SM GEM chamber is observed. The details of the experimental setup, methodology and results are reported here.
Underground experiments searching for rare events, such as interactions from dark matter, need to exhibit background as low as possible. One source of background is from cosmic ray muons and muon-induced neutron production. Presently these background are not fully understood. In this study Geant4 is used to model cosmic ray muon induced neutron multiplicity production and compare the modeling with data collected using an $^3$He instrumented Pb-target detector system. The neutron event multiplicity production is taken from the 2002 NMDS-II data sets, consisting of 6504 hrs collected at 583 m.w.e. and 1440 hrs, with the identical detector system, collected at 1166 m.w.e.. The detector consists of a 30 cm cube Pb-target surrounded by 60 $^3$He tubes. The single particle detection efficiency is 23.2\%$\pm$1.2\% calibrated using a $^{252}$Cf neutron source. The highest neutron multiplicity event, observed at 583 m.w.e. was 54 observed neutrons corresponding to $\sim$ 233 produced neutrons. The neutron multiplicity, n, distributions fit well a 2-parameter power law fit, $k\times n^{-p}$. For the Monte Carlo simulations at both depths and the data collected at both depths, all are consistent with a single slope parameter p. For the simulation at 583 m.w.e., p=2.37$\pm0.01$ and for the data collected at 583 m.w.e, p=2.36$\pm0.10$. At 1166 m.w.e., p=2.31$\pm0.01$ for the simulation, and for the data with only 6 detected events above multiplicity 5, p=$2.50 \pm 0.35$ predicted using a Maximum Likelihood Estimation method. At both depths, the power law amplitudes of the Geant4 simulations differ by a factor of 2 larger than the data sets. However, the disagreement is within the estimated systematic error of the simulations.
The production of $\psi(2S)$ mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}}=8.16$ TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb$^{-1}$. The prompt and nonprompt $\psi(2S)$ production cross-sections and the ratio of the $\psi(2S)$ to $J/\psi$ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt $\psi(2S)$ is observed to be more suppressed compared to $pp$ collisions than the prompt $J/\psi$ production, while the nonprompt productions have similar suppression factors.
The inclusive jet cross section is measured as a function of jet transverse momentum $p_\mathrm{T}$ and rapidity $y$. The measurement is performed using proton-proton collision data at $\sqrt{s}$ = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb$^{-1}$. The jets are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a distance parameter of $R$ = 0.4, within the rapidity interval $\lvert y\rvert$ $\lt$ 2, and across the kinematic range 0.06 $\lt$ $p_\mathrm{T}$ $\lt$ 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling $\alpha_\mathrm{S}$.
In recent years, there has been growing interest in the search for long-lived particles (LLPs), as predicted by various extensions of the Standard Model (SM). The AN Underground Belayed In-Shaft search experiment (ANUBIS) was proposed to search for such particles by instrumenting CERN's ATLAS underground cavern with tracking detectors. This report provides an overview of the current efforts to realize the ANUBIS project focusing on the latest optimized detector geometry and the installation of proANUBIS -- a prototype or proof-of-concept demonstrator. The latter aims to offer insights into anticipated backgrounds for the ANUBIS experiment and demonstrate the feasibility of such a project. The ongoing efforts are needed to contribute to the continuous optimization and development of the ANUBIS project.
CHIPS (CHerenkov detectors In mine PitS) was a prototype large-scale water Cherenkov detector located in northern Minnesota. The main aim of the R&D project was to demonstrate that construction costs of neutrino oscillation detectors could be reduced by at least an order of magnitude compared to other equivalent experiments. This article presents design features of the CHIPS detector along with details of the implementation and deployment of the prototype. While issues during and after the deployment of the detector prevented data taking, a number of key concepts and designs were successfully demonstrated.
Likelihood-based inference, central in modern particle physics data analysis requires the extensive evaluation of a likelihood function that depends on set of parameters defined by the statistical model under consideration. If an analytical expression for the likelihood can be defined from first principles the procedure is computationally straightforward. However, most experiments require approximating the likelihood numerically using large statistical samples of synthetic events generated using Monte Carlo methods. As a result, the likelihood consists of a comparison of the expected versus the observed event rates in a collection of histogram bins, defining binned likelihood functions. When this occurs, evaluating the likelihood function involves, on each occasion, recalculating the prediction in those bins, increasing the computational load of these analysis drastically. In this text, I highlight the importance of identifying which are the unique event configurations in the binned likelihood definition and I provide an exact formula to update the event rate predictions utilizing the minimum number of necessary calculations by means of factorization. The aim of the discussion is to decrease the computational load of widespread high-energy physics analyses, leading to substantial speed improvements and reduced carbon footprints.
Short-lived hadronic resonances are unique tools for studying the hadron-gas phase that is created in the late stages of relativistic heavy-ion collisions. Measurements of the yield ratios between resonances and the corresponding stable particles are sensitive to the competing rescattering and regeneration effects. These measurements in small collision systems, such as pp and p-Pb, are a powerful method to reveal a possible short-lived hadronic phase. In addition, resonance production in small systems is interesting to study the onset of strangeness enhancement, collective effects,and the hadron production mechanism. On this front, the $\phi$ meson is particularly relevant since its yield is sensitive to different production models: no effect is expected by strange number canonical suppression but its production is expected to be enhanced in the rope-hadronization scenario.In this presentation, recent measurements of hadronic resonances in different collision systems,going from pp to Pb-Pb collisions, are presented. These include transverse momentum spectra,yields, and yield ratios as a function of multiplicity. The presented results are discussed in the context of state-of-the-art phenomenological models of hadron production. The resonance yields measured in Pb-Pb collisions are used as an experimental input in a partial chemical equilibrium-based thermal model to constrain the kinetic freeze-out temperature. This is a novel procedure that is independent of assumptions on the flow velocity profile and the freeze-out hypersurface.
The SliT ASIC is a readout chip for the silicon strip detector to be used at the J-PARC muon $g-2$/EDM experiment. The production version of SliT128D was designed and mass production was finished. A quality assurance test method for bare SliT128D chips was developed to provide a sufficient number of chips for the experiment. The quality assurance test of the SliT128D chips was performed and 5735 chips were inspected. No defect was observed in chips of 84.3%. Accepting a few channels with poor time walk performance out of 128 channels per chip, more than 90% yield can be achieved, which is sufficient to construct the whole detector.
A statistical combination of various searches for pair-produced leptoquarks is presented, using the full LHC Run 2 (2015-2018) data set of $139$ fb$^{-1}$ collected with the ATLAS detector from proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV. All possible decays of the leptoquarks into quarks of the third generation and charged or neutral leptons of any generation are investigated. Since no significant deviations from the Standard Model expectation are observed in any of the individual analyses, combined exclusion limits are set on the production cross-sections for scalar and vector leptoquarks. The resulting lower bounds on leptoquark masses exceed those from the individual analyses by up to 100 GeV, depending on the signal hypothesis.
We present an analysis of the process $e^{+}e^{-}\to\pi^{+}\pi^{-}\Upsilon(nS)$ (where $n$ = 1, 2, or 3) reconstructed in $19.6\rm$ $\rm fb^{-1}$ of Belle II data during a special run of the SuperKEKB collider at four energy points near the peak of the $\Upsilon(10753)$ resonance. By analyzing the mass distribution of the $\pi^+\pi^-\Upsilon(nS)$ system and the Born cross sections of the $e^{+}e^{-}\to\pi^{+}\pi^{-}\Upsilon(nS)$ process, we report the first observation of $\Upsilon(10753)$ decays to the $\pi^{+}\pi^{-}\Upsilon(1S)$ and $\pi^{+}\pi^{-}\Upsilon(2S)$ final states, and find no evidence for decays to $\pi^{+}\pi^{-}\Upsilon(3S)$. Possible intermediate states in the $\pi^+\pi^-\Upsilon(1S,2S)$ transitions are also investigated, and no evidence for decays proceeding via the $\pi^\mp Z_b^\pm$ or $f_0(980)\Upsilon(nS)$ intermediate states is found. We measure Born cross sections for the $e^{+}e^{-}\to\pi^{+}\pi^{-}\Upsilon(nS)$ process that, combined with results from Belle, improve the precision of measurements of the $\Upsilon(10753)$ mass and width by nearly a factor of two to $(10756.3\pm2.7\pm0.6)$ MeV/$c^2$ and $(29.7\pm8.5\pm1.1)$ MeV, respectively. The relative ratios of the Born cross sections at the $\Upsilon(10753)$ resonance peak are also reported for the first time.
Environmental $\gamma$-rays constitute a crucial source of background in various nuclear, particle and quantum physics experiments. To evaluate the flux rate and the spectrum of $\gamma$ background, we have developed a novel and straightforward approach to reconstruct the environmental $\gamma$ flux spectrum by applying a portable CZT $\gamma$ detector and iterative Bayesian unfolding, which possesses excellent transferability for broader applications. In this paper, the calibration and GEANT4 Monte-Carlo modeling of the CZT detector, the unfolding procedure as well as the uncertainty estimation are demonstrated in detail. The reconstructed spectrum reveals an environmental $\gamma$ flux intensity of $3.3\pm 0.3\times 10^{7}$ (m$^2\cdot$sr$\cdot$hour)$^{-1}$ ranging from 73 to 3033 keV, along with characteristic peaks primarily arising from $^{232}$Th series, $^{238}$U series and $^{40}$K. We also give an instance of background rate evaluation with the unfolded spectrum for validation of the approach.
Jet flavor tagging plays a crucial role in the measurement of relative partial decay widths of $Z$ boson, denoted as $R_b$($R_c$), which is considered as a fundamental test of the Standard Model and sensitive probe to new physics. In this study, a Deep Learning algorithm, ParticleNet, is employed to enhance the performance of jet flavor tagging. The combined efficiency and purity of $c$-tagging is improved by more than 50\% compared to the Circular Electron Positron Collider (CEPC) baseline software. In order to measure $R_b$($R_c$) with this new flavor tagging approach, we have adopted the double-tagging method. The precision of $R_b$($R_c$) is improved significantly, in particular to $R_c$, which has seen a reduction in statistical uncertainty by 40\%.
A measurement of the mass of the Higgs boson combining the $H\to ZZ^{*} \to 4\ell$ and $H\to\gamma\gamma$ decay channels is presented. The result is based on 140 fb$^{-1}$ of proton-proton collision data collected by the ATLAS detector during LHC Run 2 at a centre-of-mass energy of 13 TeV combined with the Run 1 ATLAS mass measurement, yielding a Higgs boson mass of 125.11 $\pm$ 0.09 (stat.) $\pm$ 0.06 (syst.) = 125.11 $\pm$ 0.11 GeV. This corresponds to a 0.09 % precision achieved on this fundamental parameter of the Standard Model of particle physics.
Based on $4.4~\text{fb}^{-1}$ of $e^{+}e^{-}$ annihilation data collected at the center-of-mass energies between $4.60$ and $4.70~\text{GeV}$ with the BESIII detector at the BEPCII collider, the pure \textit{W}-boson-exchange decay $\Lambda_{c}^{+}\to\Xi^{0}K^{+}$ is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be $\alpha_{\Xi^{0}K^{+}}=0.01\pm0.16({\rm stat.})\pm0.03({\rm syst.})$. This result reflects the non-interference effect between the $S$- and $P$-wave amplitudes. The phase shift between $S$- and $P$-wave amplitudes has two solutions, which are $\delta_{p}-\delta_{s}=-1.55\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad}$ or $1.59\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad}$.
The prototype of a TDC board has been developed for the new high granular time-of-flight neutron detector (HGND). The board is based on the standard LVDS 4x asynchronous oversampling using the xc7k160 FPGA with a 100 ps bin width. The HGND is being developed for the BM@N (Baryonic Matter at Nuclotron) experiment to identify neutrons and to measure their energies in heavy-ion collisions at ion beam energies up to 4 A GeV. The HGND consists of about 2000 scintillator detectors (cells) with a size of $40 \times 40 \times 25 mm^3$ and light readout with EQR15 11-6060D-S photodetectors. To measure the time resolution of the scintillator cells, the two-channel FPGA TDC board prototype with two scintillator cells was tested with an electron beam of "Pakhra" synchrotron at the LPI institute (Moscow, Russia). The measured cell time resolution is 146 ps, which is in a good agreement with the 142 ps time resolution measured with a 12-bit @ 5 GS/s CAEN DT5742 digitizer. For the full HGND, the TDC readout board with three such FPGAs will read 250 channels. In total, eight such TDC boards will be used for the full HGND at the BM@N experiment.
We have analyzed 121.4 fb$^{-1}$ of data collected at the $\Upsilon(5S)$ resonance by the Belle experiment using the KEKB asymmetric-energy $e^+e^-$ collider to search for the decay $B_s^0\to J/\psi\pi^0$. We observe no signal and report an upper limit on the branching fraction $\mathcal{B}(B_s^0\to J/\psi\pi^0)$ of $1.21\times 10^{-5}$ at 90\% confidence level. This result is the most stringent, improving the previous bound by two orders of magnitude.
Rare event search experiments using germanium detectors are operated in underground laboratories to minimize the background induced by cosmic rays. However, the cosmogenic activation in germanium crystals on the ground during fabrication and transportation generates long half-life radionuclides and contributes a considerable background. We simulated the production rates of cosmogenic radionuclides in germanium and calculated the specifi c activities of cosmogenic radionuclides according to the scheduled fabrication and transportation processes of $^{76}$Ge enriched germanium detectors. The impact of cosmogenic background in germanium crystals for the next generation CDEX experiment was assessed with the scheduled exposure history above ground.
We present the results of a beam test conducted on a telescope utilizing the JadePix-3 pixel sensor, which was developed with TowerJazz 180 nm CMOS imaging technology. The telescope is composed of five planes, each equipped with a JadePix-3 sensor with pitches of 26um x 16um and 23.11um x 16um. Additionally, it features an FPGA-based synchronous readout system. The telescope underwent testing using an electron beam with energy ranging from 4 GeV to 6 GeV. At the electron energy of 5.4 GeV, the telescope demonstrated a superior spatial resolution of 2.6 um and 2.3 um in two dimensions, respectively. By designating the central plane as the Device Under Test, we evaluated the JadePix-3 sensor's spatial resolution of 5.2 um and 4.6 um in two dimensions, achieving a detection efficiency of over 99%.
Cryptocurrency mining processes always lead to a high energy consumption at considerably high production cost, which is nearly one-third of cryptocurrency (e.g. Bitcoin) price itself. As the core of mining process is based on SHA-256 cryptographic hashing function, by using the alternative quantum computers, hybrid quantum computers or more larger quantum computing devices like quantum annealers, it would be possible to reduce the mining energy consumption with a quantum hardware's low-energy-operation characteristics. Within this work we demonstrated the use of optimized quantum mining facilities which would replace the classical SHA-256 and high energy consuming classical hardware in near future.
Particle-particle interaction provides a new degree of freedom to induce novel topological phenomena. Here, we propose to use spatiotemporal modulation of interaction to realize topological pumping without single-particle counterpart. Because the modulation breaks time-reversal symmetry, the multiparticle energy bands of bound states have none-zero Chern number, and support topological bound edge states. In a Thouless pump, a bound state that uniformly occupies a topological energy band can be shifted by integer unit cells per cycle, consistent with the corresponding Chern number. We can also realize topological pumping of bound edge state from one end to another. The entanglement entropy between particles rapidly increases at transition points, which is related to the spatial spread of a bounded pair. In addition, we propose to realize hybridized pumping with fractional displacement per cycle by adding an extra tilt potential to separate topological pumping of the bound state and Bloch oscillations of single particle. Our work could trigger further studies of correlated topological phenomena that do not have a single-particle counterpart.
Exceptional points of order $n$ (EP$n$s) appear in non-Hermitian systems as points where the eigenvalues and eigenvectors coalesce. Whereas EP2s generically appear in two dimensions (2D), higher-order EPs require a higher-dimensional parameter space to emerge. In this work, we provide a complete characterization the appearance of symmetry-induced higher-order EPs in 2D parameter space. We find that besides EP2s only EP3s, EP4s, and EP5s can be stabilized in 2D. Moreover, these higher-order EPs must always appear in pairs with their dispersion determined by the symmetries. Upon studying the complex spectral structure around these EPs, we find that depending on the symmetry, EP3s are accompanied by EP2 arcs, and 2- and 3-level open Fermi structures. Similarly, EP4s and closely related EP5s, which arise due to multiple symmetries, are accompanied by exotic EP arcs and open Fermi structures. For each case, we provide an explicit example. We also comment on the topological charge of these EPs, and discuss similarities and differences between symmetry-protected higher-order EPs and EP2s.
Fault-tolerant architectures aim to reduce the noise of a quantum computation. Despite such architectures being well studied a detailed understanding of how noise is transformed in a fault-tolerant primitive such as magic state injection is currently lacking. We use numerical simulations of logical process tomography on a fault-tolerant gadget that implements a logical T = $Z({\pi}/8)$ gate using magic state injection, to understand how noise characteristics at the physical level are transformed into noise characteristics at the logical level. We show how, in this gadget, a significant phase ($Z$) bias can arise in the logical noise, even with unbiased noise at the physical level. While the magic state injection gadget intrinsically induces biased noise, with extant phase bias being further amplified at the logical level, we identify noisy error correction circuits as a key limiting factor on the magnitude of this logical noise bias. Our approach provides a framework for assessing the detailed noise characteristics, as well as the overall performance, of fault-tolerant logical primitives.
Understanding how non-adiabatic terms affect quantum dynamics is fundamental to improving various protocols for quantum technologies. We present a novel approach to computing the Adiabatic Gauge Potential (AGP), which gives information on the non-adiabatic terms that arise from time dependence in the Hamiltonian. Our approach uses commutators of the Hamiltonian to build up an appropriate basis of the AGP, which can be easily truncated to give an approximate form when the exact result is intractable. We use this approach to study the AGP obtained for the transverse field Ising model on a variety of graphs, showing how the different underlying graph structures can give rise to very different scaling for the number of terms required in the AGP.
We construct an observable mixed state topological order parameter for symmetry-protected free fermion matter. It resolves the entire table of topological insulators and superconductors, relying exclusively on the symmetry class, but not on unitary symmetries. It provides a robust, quantized signal not only for pure ground states, but also for mixed states in- or out of thermal equilibrium. Key ingredient is a unitary probe operator, whose phase can be related to spectral asymmetry, in turn revealing the topological properties of the underlying state. This is demonstrated analytically in the continuum limit, and validated numerically on the lattice. The order parameter is experimentally accessible via either interferometry or full counting statistics, for example, in cold atom experiments.
A fundamental problem in quantum thermodynamics is to properly quantify the work extractable from out-of-equilibrium systems. While for closed systems, maximum quantum work extraction is defined in terms of the ergotropy functional, this question is unclear in open systems interacting with an environment. The concept of local ergotropy has been proposed, but it presents several problems, such as it is not guaranteed to be non-increasing in time. Here we introduce the concept of extended local ergotropy by exploiting the free evolution of the system-environment compound. At variance with the local ergotropy, the extended local ergotropy is greater, is non-increasing in time, and activates the potential of work extraction in many cases. We then concentrate on specific schemes in which we alternate repeated local unitaries and free SE evolution. We provide examples based on the Jaynes-Cummings model, presenting practical protocols and analytic results that serve as proof of principle for the aforementioned advantages.
We develop qutrit circuit models for discrete-time three-state quantum walks on Cayley graphs corresponding to Dihedral groups $D_N$ and the additive groups of integers modulo any positive integer $N$. The proposed circuits comprise of elementary qutrit gates such as qutrit rotation gates, qutrit-$X$ gates and two-qutrit controlled-$X$ gates. First, we propose qutrit circuit representation of special unitary matrices of order three, and the block diagonal special unitary matrices with $3\times 3$ diagonal blocks, which correspond to multi-controlled $X$ gates and permutations of qutrit Toffoli gates. We show that one-layer qutrit circuit model need $O(3nN)$ two-qutrit control gates and $O(3N)$ one-qutrit rotation gates for these quantum walks when $N=3^n$. Finally, we numerically simulate these circuits to mimic its performance such as time-averaged probability of finding the walker at any vertex on noisy quantum computers. The simulated results for the time-averaged probability distributions for noisy and noiseless walks are further compared using KL-divergence and total variation distance. These results show that noise in gates in the circuits significantly impacts the distributions than amplitude damping or phase damping errors.
The Symmetric Informationally Complete Positive Operator-Valued Measures (SIC-POVMs) are known to exist in all dimensions $\leq 151$ and few higher dimensions as high as $1155$. All known solutions with the exception of the Hoggar solutions are covariant with respect to the Weyl-Heisenberg group and in the case of dimension 3 it has been proven that all SIC-POVMs are Weyl-Heisenberg group covariant. In this work, we introduce two functions with which SIC-POVM Gram matrices can be generated without the group covariance constraint. We show analytically that the SIC-POVM Gram matrices exist on critical points of surfaces formed by the two functions on a subspace of symmetric matrices and we show numerically that in dimensions 4 to 7, all SIC-POVM Gram matrices lie in disjoint solution "islands". We generate $O(10^6)$ and $O(10^5)$ Gram matrices in dimensions 4 and 5, respectively and $O(10^2)$ Gram matrices in dimensions 6 and 7. For every Gram matrix obtained, we generate the symmetry groups and show that all symmetry groups contain a subgroup of $3n^2$ elements. The elements of the subgroup correspond to the Weyl-Heisenberg group matrices and the order-3 unitaries that generate them. All constructed Gram matrices have a unique generating set. Using this fact, we generate permutation matrices to map the Gram matrices to known Weyl-Heisenberg group covariant solutions. In dimensions 4 and 5, the absence of a solution with a smaller symmetry, strongly suggests that non-group covariant SIC-POVMs cannot be constructed.
We isolate a class of exact quantum master equations (EQMEs) to capture the dynamics of open quantum systems coupled to bosonic thermal baths of arbitrary complexity. This is done by mapping this dynamics into that of the system in interaction with a few collective bath excitations or bexcitons. The bexcitons emerge from a decomposition of the bath correlation function. Their properties, while unphysical, offer a coarse-grained view of the correlated system-bath dynamics that can be used to design efficient EQMEs. The approach provides a systematic strategy to construct EQMEs that include the system-bath coupling to all orders even for non-Markovian environments and contains the well-known hierarchical equation of motion method as a special case.
We demonstrate coherent control of the fine-structure qubit in neutral strontium atoms. This qubit is encoded in the metastable $^3\mathrm{P}_2$ and $^3\mathrm{P}_0$ states, coupled by a Raman transition. Using a magnetic quadrupole transition, we demonstrate coherent state-initialization of this THz qubit. We show Rabi oscillations with more than 60 coherent cycles and single-qubit rotations on the $\mu$s scale. With spin-echo, we demonstrate coherence times of tens of ms. Our results pave the way for fast quantum information processors and highly tunable quantum simulators with two-electron atoms.
An important property of QAOA with Grover mixer is that its expectation value is invariant over any permutation of states. As a consequence, the algorithm is independent of the structure of the problem. If, on the one hand, this characteristic raises serious doubts about the capacity of the algorithm to overcome the bound of the unstructured search problem, on the other hand, it can pave the way to its analytical study. In this sense, a prior work introduced a statistical approach to analyze GM-QAOA that results in an analytical expression for the expectation value depending on the probability distribution associated with the problem Hamiltonian spectrum. Although the method provides surprising simplifications in calculations, the expression depends exponentially on the number of layers, which makes direct analytical treatment unfeasible. In this work, we extend the analysis to the more simple context of Grover Mixer Threshold QAOA (GM-Th-QAOA), a variant that replaces the phase separation operator of GM-QAOA to encode a threshold function. As a result, we obtain an expression for the expected value independent of the number of layers and, with it, we provide bounds for different performance metrics. Furthermore, we extend the analysis to a more general context of QAOA with Grover mixer, which we called Grover-based QAOA. In that framework, which allows the phase separation operator to encode any compilation of the cost function, we generalize all the bounds by using a contradiction argument with the optimality of Grover's algorithm on the unstructured search problem. The main result is an asymptotic tight bound on the quantile achieved by the expectation value that formalizes the notion that the Grover mixer reflected a quadratic Grover-style speed-up over brute force. We apply that bound on the Max-Cut problem to the particular class of complete bipartite graphs.
We investigate both theoretically and numerically the dynamics of Out-of-Time-Ordered Correlators (OTOCs) in quantum resonance condition for a kicked rotor model. We employ various operators to construct OTOCs in order to thoroughly quantify their commutation relation at different time, therefore unveiling the process of quantum scrambling. With the help of quantum resonance condition, we have deduced the exact expressions of quantum states during both forward evolution and time reversal, which enables us to establish the laws governing OTOCs' time dependence. We find interestingly that the OTOCs of different types increase in a quadratic function of time, breaking the freezing of quantum scrambling induced by the dynamical localization under non-resonance condition. The underlying mechanism is discovered and the possible applications in quantum entanglement are discussed.
We investigate the dynamics of quantum scrambling, characterized by the out-of-time ordered correlators (OTOCs), in a non-Hermitian quantum kicked rotor subjected to quasi-periodical modulation in kicking potential. Quasi-periodic modulation with incommensurate frequencies creates a high-dimensional synthetic space, where two different phases of quantum scrambling emerge: the freezing phase characterized by the rapid increase of OTOCs towards saturation, and the chaotic scrambling featured by the linear growth of OTOCs with time. We find the dynamical transition from the freezing phase to the chaotic scrambling phase, which is assisted by increasing the real part of the kicking potential along with a zero value of its imaginary part. The opposite transition occurs with the increase in the imaginary part of the kicking potential, demonstrating the suppression of quantum scrambling by non-Hermiticity. The underlying mechanism is uncovered by the extension of the Floquet theory. Possible applications in the field of quantum information are discussed.
Simulating quantum circuits on classical hardware is a powerful and necessary tool for developing and testing quantum algorithms and hardware as well as evaluating claims of quantum supremacy in the Noisy Intermediate-Scale Quantum (NISQ) regime. Schr\"odinger-style simulations are limited by the exponential growth of the number of state amplitudes which need to be stored. In this work, we apply scalar and vector quantization to Schr\"odinger-style quantum circuit simulations as lossy compression schemes to reduce the number of bits needed to simulate quantum circuits. Using quantization, we can maintain simulation fidelities $>0.99$ when simulating the Quantum Fourier Transform, while using only 7 significand bits in a floating-point number to characterize the real and imaginary components of each amplitude. Furthermore, using vector quantization, we propose a method to bound the number of bits/amplitude needed to store state vectors in a simulation of a circuit that achieves a desired fidelity, and show that for a 6 qubit simulation of the Quantum Fourier Transform, 15 bits/amplitude is sufficient to maintain fidelity $>0.9$ at $10^4$ depth.
Quantum kernels hold great promise for offering computational advantages over classical learners, with the effectiveness of these kernels closely tied to the design of the quantum feature map. However, the challenge of designing effective quantum feature maps for real-world datasets, particularly in the absence of sufficient prior information, remains a significant obstacle. In this study, we present a data-driven approach that automates the design of problem-specific quantum feature maps. Our approach leverages feature-selection techniques to handle high-dimensional data on near-term quantum machines with limited qubits, and incorporates a deep neural predictor to efficiently evaluate the performance of various candidate quantum kernels. Through extensive numerical simulations on different datasets, we demonstrate the superiority of our proposal over prior methods, especially for the capability of eliminating the kernel concentration issue and identifying the feature map with prediction advantages. Our work not only unlocks the potential of quantum kernels for enhancing real-world tasks but also highlights the substantial role of deep learning in advancing quantum machine learning.
In this study, a compact and low-power-consumption quantum random number generator (QRNG) based on a laser diode and silicon photonics integrated hybrid chip is proposed and verified experimentally. The hybrid chip's size is 8.8*2.6*1 mm3, and the power of entropy source is 80 mW. A common mode rejection ratio greater than 40 dB was achieved using an optimized 1*2 multimode interferometer structure. A method for optimizing the quantum-to-classical noise ratio is presented. A quantum-to-classical noise ratio of approximately 9 dB was achieved when the photoelectron current is 1 microampere using a balance homodyne detector with a high dark current GeSi photodiode. The proposed QRNG has the potential for use in scenarios of moderate MHz random number generation speed, with low power, small volume, and low cost prioritized.
High-fidelity quantum gates are essential prerequisite for large-scale quantum computation. When manipulating practical quantum systems, environmental and operational induced errors are inevitable, and thus, besides to be fast, operations are more preferable to be intrinsically robust against different errors. Here, we propose a general protocol to construct geometric quantum gates with on demanded trajectory, by modulating the applied pulse shapes that define the system's evolution trajectory. Our scheme adopts a reverse engineering of the target Hamiltonian by using smooth pulses, which also removes the difficulty of calculating geometric phases for an arbitrary trajectory. Besides, as a certain geometric gate can be induced by various trajectories, we can further optimize the gate performance under different scenarios, and numerical simulations indicate that this optimization can greatly enhance its quality. Therefore, our protocol presents a promising approach for high-fidelity and strong-robust geometric quantum gates for large-scale quantum computation.
Classical probability theory is based on assumptions which are often violated in practice. Therefore quantum probability is a proposed alternative not only in quantum physics, but also in other sciences. However, so far it mostly criticizes the classical approach, but does not suggest a working alternative. Maximum likelihood estimators were given very low attention in this context. We show that they can be correctly defined and their computation in closed form is feasible at least in some cases.
One of the major benefits of quantum computing is the potential to resolve complex computational problems faster than can be done by classical methods. There are many prototype-based clustering methods in use today, and selection of the starting nodes for the center points is often done randomly. For prototype-based clustering algorithms, this could lead to much slower convergence times. One of the causes of this may be prototype-based clustering accepting a local minima as a valid solution when there are possibly better solutions. Quantum computing, specifically quantum annealing, offers a solution to these problems by mapping the initial centroid problem to an Ising Hamiltonian where over time the lowest energy in the spectrum correlates to a valid, but better solution. A first approach to this problem utilizing quantum annealing was known as Quantum Optimized Centroid Initialization (QOCI), but this approach has some limitations both in results and performance. We will present a modification of QOCI known as Adaptive Quantum Optimized Centroid Initialization (AQOCI) which addresses many of the limitations in QOCI. The results presented are comparable to those obtained using classical techniques as well as being superior to those results found using QOCI.
The phenomenon of Hilbert space fragmentation, whereby dynamical constraints fragment Hilbert space into many disconnected sectors, provides a simple mechanism by which thermalization can be arrested. However, little is known about how thermalization occurs in situations where the constraints are not exact. To study this, we consider a situation in which a fragmented 1d chain with pair-flip constraints is coupled to a thermal bath at its boundary. For product states quenched under Hamiltonian dynamics, we numerically observe an exponentially long thermalization time, manifested in both entanglement dynamics and the relaxation of local observables. To understand this, we study an analogous model of random unitary circuit dynamics, where we rigorously prove that the thermalization time scales exponentially with system size. Slow thermalization in this model is shown to be a consequence of strong bottlenecks in configuration space, demonstrating a new way of producing anomalously slow thermalization dynamics.
We treat disordered Heisenberg model in 1D as the "standard model" of many-body localization (MBL). Two independent order parameters stemming purely from the half-chain von Neumann entanglement entropy $S_{\textrm{vN}}$ are introduced to probe its eigenstate transition. From symmetry-endowed entropy decomposition, they are probability distribution deviation $|d(p_n)|$ and von Neumann entropy $S_{\textrm{vN}}^{n}(D_n\!=\!\mbox{max})$ of the maximum-dimensional symmetry subdivision. Finite-size analyses reveal that $\{p_n\}$ drives the localization transition, preceded by a thermalization breakdown transition governed by $\{S_{\textrm{vN}}^{n}\}$. For noninteracting case, these transitions coincide, but in interacting situation they separate. Such separability creates an intermediate phase region and may help discriminate between the Anderson and MBL transitions. An obstacle whose solution eludes community to date is the violation of Harris criterion in nearly all numeric investigations of MBL so far. Upon elucidating the mutually independent components in $S_{\textrm{vN}}$, it is clear that previous studies of eigenspectra, $S_{\textrm{vN}}$, and the like lack resolution to pinpoint (thus completely overlook) the crucial internal structures of the transition. We show, for the first time, that after this necessary decoupling, the universal critical exponents for both transitions of $|d(p_n)|$ and $S_{\textrm{vN}}^{n}(D_n\!=\!\mbox{max})$ fulfill the Harris criterion: $\nu\approx2.0\ (\nu\approx1.5)$ for quench (quasirandom) disorder. Our work puts forth "symmetry combined with entanglement" as the missing organization principle for the generic eigenstate matter and transition.
Quantum machine learning, which involves running machine learning algorithms on quantum devices, has garnered significant attention in both academic and business circles. In this paper, we offer a comprehensive and unbiased review of the various concepts that have emerged in the field of quantum machine learning. This includes techniques used in Noisy Intermediate-Scale Quantum (NISQ) technologies and approaches for algorithms compatible with fault-tolerant quantum computing hardware. Our review covers fundamental concepts, algorithms, and the statistical learning theory pertinent to quantum machine learning.
Quantum circuit simulation is a challenging computational problem crucial for quantum computing research and development. The predominant approaches in this area center on tensor networks, prized for their better concurrency and less computation than methods using full quantum vectors and matrices. However, even with the advantages, array-based tensors can have significant redundancy. We present a novel open-source framework that harnesses tensor decision diagrams to eliminate overheads and achieve significant speedups over prior approaches. On average, it delivers a speedup of 37$\times$ over Google's TensorNetwork library on redundancy-rich circuits, and 25$\times$ and 144$\times$ over quantum multi-valued decision diagram and prior tensor decision diagram implementation, respectively, on Google random quantum circuits. To achieve this, we introduce a new linear-complexity rank simplification algorithm, Tetris, and edge-centric data structures for recursive tensor decision diagram operations. Additionally, we explore the efficacy of tensor network contraction ordering and optimizations from binary decision diagrams.
We propose a new method, "counter-factual" carving, that uses the "no-jump" evolution of a probe to generate entangled many-body states of high fidelity. The probe is coupled to a target ensemble of qubits and engineered to exponentially decay at a rate depending on the target collective spin, such that post-selecting on observing no probe decay precisely removes select faster-decaying spin components. When probe and $N$-qubit target interact via a cavity mode of cooperativity $C$, counter-factual carving generates entangled states with infidelities of $e^{-C/N}$, an exponential improvement over previous carving schemes. Counter-factual carving can generate complex entangled states for applications in quantum metrology and quantum computing.
Obeying non-Abelian statistics, Majorana fermion holds a promise to implement topological quantum computing. It was found that Majorana fermion can be simulated by the zero-energy excitation in a semiconducting nanowire with strong spin-orbit coupling interacting with a $s$-wave superconductor under a magnetic field. We here propose an alternative scheme to simulate the Majorana fermion in a trapped-ion system. Our dimitrized-ion configuration permits us to generate the Majorana modes not only at zero energy but also at the nonzero ones. We also investigate the controllability of the Majorana modes by Floquet engineering. It is found that a widely tunable number of Majorana modes are created on demand by applying a periodic driving on a topologically trivial trapped-ion system. Enriching the platforms for simulating Majorana fermion, our result would open another avenue for realizing topological quantum computing.
We present a hybrid quantum-classical Green's function Monte Carlo (GFMC) algorithm for estimating the excited states of the nuclear shell model. The conventional GFMC method, widely used to find the ground state of a quantum many-body system, is plagued by the sign problem, which leads to an exponentially increasing variance with the growth of system size and evolution time. This issue is typically mitigated by applying classical constraints but at the cost of introducing bias. Our approach uses quantum subspace diagonalization (QSD) on a quantum computer to prepare a quantum trial state, replacing the classical trial state in the GFMC process. We also incorporated a modified classical shadow technique in the implementation of QSD to optimize quantum resource utilization. Besides, we extend our hybrid GFMC algorithm to find the excited states of a given quantum system. Numerical results suggest our method largely enhances accuracy in determining excited state energies, offering an improvement over the conventional method.
It is known that the excitations in graphene-like materials in external electromagnetic field are described by solutions of massless two-dimensional Dirac equation which includes both Hermitian off-diagonal matrix and scalar potentials. Up to now, such two-component wave functions were calculated for different forms of external potentials but, as a rule, depending on one spatial variable only. Here, we shall find analytically the solutions for a wide class of combinations of matrix and scalar external potentials which physically correspond to applied mutually orthogonal magnetic and longitudinal electrostatic fields, both depending really on two spatial variables. The main tool for this progress was provided by supersymmetrical (SUSY) intertwining relations, namely, by their most general - asymmetrical - form proposed recently by the authors. Such SUSY-like method is applied in two steps similarly to the second order factorizable (reducible) SUSY transformations in ordinary Quantum Mechanics.
Reinforcement Learning (RL) consists of designing agents that make intelligent decisions without human supervision. When used alongside function approximators such as Neural Networks (NNs), RL is capable of solving extremely complex problems. Deep Q-Learning, a RL algorithm that uses Deep NNs, achieved super-human performance in some specific tasks. Nonetheless, it is also possible to use Variational Quantum Circuits (VQCs) as function approximators in RL algorithms. This work empirically studies the performance and trainability of such VQC-based Deep Q-Learning models in classic control benchmark environments. More specifically, we research how data re-uploading affects both these metrics. We show that the magnitude and the variance of the gradients of these models remain substantial throughout training due to the moving targets of Deep Q-Learning. Moreover, we empirically show that increasing the number of qubits does not lead to an exponential vanishing behavior of the magnitude and variance of the gradients for a PQC approximating a 2-design, unlike what was expected due to the Barren Plateau Phenomenon. This hints at the possibility of VQCs being specially adequate for being used as function approximators in such a context.
Inspired by the narrow Feshbach resonance in systems with the two-body interaction, we propose the two-channel model of three-component fermions with the three-body interaction that takes into account the finite-range effects in low dimensions. Within this model, the $p$-wave Efimov-like effect in the four-body sector is predicted in fractional dimensions above 1D. The impact of the finite-range interaction on the formation of the four-body bound states in $d=1$ is also discussed in detail.
Utilizing unsupervised representation learning for quantum architecture search (QAS) represents a cutting-edge approach poised to realize potential quantum advantage on Noisy Intermediate-Scale Quantum (NISQ) devices. Most QAS algorithms combine their search space and search algorithms together and thus generally require evaluating a large number of quantum circuits during the search process. Predictor-based QAS algorithms can alleviate this problem by directly estimating the performance of circuits according to their structures. However, a high-performance predictor generally requires very time-consuming labeling to obtain a large number of labeled quantum circuits. Recently, a classical neural architecture search algorithm Arch2vec inspires us by showing that architecture search can benefit from decoupling unsupervised representation learning from the search process. Whether unsupervised representation learning can help QAS without any predictor is still an open topic. In this work, we propose a framework QAS with unsupervised representation learning and visualize how unsupervised architecture representation learning encourages quantum circuit architectures with similar connections and operators to cluster together. Specifically, our framework enables the process of QAS to be decoupled from unsupervised architecture representation learning so that the learned representation can be directly applied to different downstream applications. Furthermore, our framework is predictor-free eliminating the need for a large number of labeled quantum circuits. During the search process, we use two algorithms REINFORCE and Bayesian Optimization to directly search on the latent representation, and compare them with the method Random Search. The results show our framework can more efficiently get well-performing candidate circuits within a limited number of searches.
We theoretically explore the generation of entangled two-photon pairs through Cooper pair recombination within a noncentrosymmetric [001]-quantum well superconductor. Superconducting state is induced into the quantum well via proximity effects, and featuring an admixture of Rashba and Dresselhaus antisymmetric spin-orbit couplings. Our investigation highlights that the highest achievable purity of entangled photon pairs emerges within scenarios involving pure singlet Cooper pairs. Specifically, the conventional $s$-wave gap function within the singlet pairings achieves the highest purity levels. Furthermore, our findings underscore the significance of reducing spin-triplet pairing amplitudes to attain entangled states of superior purity. This reduction can be achieved by diminishing the amplitude of antisymmetric spin-orbit couplings. In addition to purity considerations, our study delves into the population of two-photon states. We observed that states featuring $s+p$- and $d^{}_{x^2-y^2}+p$-wave Cooper pairings exhibit the highest population values among the generated entangled two-photon states within a noncentrosymmetric superconducting quantum well.
Elliptic curves are planar curves which can be used to define an abelian group. The efficient computation of discrete logarithms over this group is a longstanding problem relevant to cryptography. It may be possible to efficiently compute these logarithms using a quantum computer, assuming that the group addition operation can be computed efficiently on a quantum device. Currently, however, thousands of logical qubits are required for elliptic curve group addition, putting this application out of reach for near-term quantum hardware. Here we give an algorithm for computing elliptic curve group addition using a single continuous-variable mode, based on weak measurements of a system with a cubic potential energy. This result could lead to improvements in the efficiency of elliptic curve discrete logarithms using a quantum device.
We introduce the technique of Entangled-Beam Reflectometry for extracting spatially correlated (magnetic or non-magnetic) information from material surfaces or thin films. Our amplitude- and phase-sensitive technique exploits the coherent nature of an incoming entangled probe beam, of matter or light waves, undergoing reflection from the surface. Such reflection encodes the surface spatial structure into the probe's geometric and phase-derived Goos-H\"anchen shifts, which can then be measured to unveil the structure. We investigate the way these shifts depend on the wave packet widths, and illustrate our technique in the case of in-plane periodic (non-)magnetic structures by utilizing spin-path mode-entangled neutron beams.
When the strength of interaction between a quantum system and bath is non-negligible, the equilibrium state can deviate from the Gibbs state. Here, we obtain an approximate expression for such a mean force Gibbs state for a particle in an arbitrary one dimensional potential, interacting with a bosonic bath. This approximate state is accurate when either the system-bath coupling or the temperature is large, or when the third and higher derivatives of the potential are small compared to certain system-bath specific parameters. We show that our result recovers the ultra strong coupling and high temperature results recently derived in literature. We then apply this method to study some systems like a quartic oscillator and a particle in a quartic double-well potential. We also use our method to analyze the proton tunneling problem in a DNA recently studied in literature [Slocombe et al., Comm. Phys., vol. 5, no. 1, p. 109, 2022], where our results suggest the equilibrium value of the probability of mutation to be orders of magnitude lower than the steady state value obtained there ($10^{-8}$ vs $10^{-4}$).
We propose using the dynamical invariant also known as the Lewis-Riesenfeld invariant, to speed-up the equilibration of a driven open quantum system. This allows us to reverse engineer the time-dependent master equation that describes the dynamics of the open quantum system and systematically derive a protocol that realizes a shortcut to equilibration. The method does not require additional constraints on the timescale of the dynamics beside the Born-Markov approximation and can be generically applied to boost single particle quantum engines significantly. We demonstrate it with the damped harmonic oscillator, and show that our protocol can achieve a high-fidelity control in shorter timescales than simple non-optimized protocols. We find that the system is heated during the dynamics to speed-up the equilibration, which can be considered as an analogue of the Mpemba effect in quantum control.
The dynamics of quantum discord is studied in a system of two identical noninteracting qubits coupled to a common squeezed vacuum bath through non-demolition interactions. We concern on how reservoir squeezing influences the dynamical behaviors of quantum discord when both qubits are initially prepared in $X$-type states. We find that the critical time exhibits the sudden change of quantum discord, which is of great significance for the quantum discord amplification. Furthermore, depending on the initial parameters of the system, we numerically calculate the interval when the critical time is finite or infinite. For the finite critical time, we show that the squeezing phase of the bath can prolong the critical time while the squeezing strength exhibits the opposite effect. For infinite critical time, even if there is no sudden transition point, reservoir squeezing still has an effect on the amplification of quantum discord, and the time to reach steady-state quantum discord can be changed by adjusting the squeezing parameters. Fianlly, we investigate the quantum speed limit time for a two-qubit system under squeezed reservoir, and find that the quantum speed limit time can be reduced via the adjustment of the squeezing parameters and the initial parameters. Remarkably, in the short time limit, reservoir squeezing has an obvious influence on the degree of amplification of quantum discord. Our study presents a promising approach to controlling the amplification of quantum correlation.
Consciousness within the brain hinges on the synchronized activities of millions of neurons, but the mechanism responsible for orchestrating such synchronization remains elusive. In this study, we employ cavity quantum electrodynamics (cQED) to explore entangled biphoton generation through cascade emission in the vibration spectrum of C-H bonds within the lipid molecules' tails. The results indicate that the cylindrical cavity formed by a myelin sheath can facilitate spontaneous photon emission from the vibrational modes and generate a significant number of entangled photon pairs. The abundance of C-H bond vibration units in neurons can therefore serve as a source of quantum entanglement resources for the nervous system. The finding may offer insight into the brain's ability to leverage these resources for quantum information transfer, thereby elucidating a potential source for the synchronized activity of neurons.
We propose a scheme to entangle two magnon modes based on parity measurement. In particular, we consider a system that two yttrium-iron-garnet spheres are coupled to a $V$-type superconducting qutrit through the indirect interactions mediated by cavity modes. An effective parity-measurement operator that can project the two macroscopic spin systems to the desired subspace emerges when the ancillary qutrit is projected to the ground state. Consequently, conventional and multi-excitation magnon Bell states can be generated from any separable states with a nonvanishing population in the desired subspace. The target state can be distilled with a near-to-unit fidelity only by several rounds of measurements and can be stabilized in the presence of decoherence. In addition, a single-shot version of our scheme is obtained by shaping the detuning in the time domain. Our scheme that does not rely on any nonlinear effect brings insight to the entangled-state generation in massive ferrimagnetic materials via quantum measurement.
We present a general class of machine learning algorithms called parametric matrix models. Parametric matrix models are based on matrix equations, and the design is motivated by the efficiency of reduced basis methods for approximating solutions of parametric equations. The dependent variables can be defined implicitly or explicitly, and the equations may use algebraic, differential, or integral relations. Parametric matrix models can be trained with empirical data only, and no high-fidelity model calculations are needed. While originally designed for scientific computing, parametric matrix models are universal function approximators that can be applied to general machine learning problems. After introducing the underlying theory, we apply parametric matrix models to a series of different challenges that show their performance for a wide range of problems. For all the challenges tested here, parametric matrix models produce accurate results within a computational framework that allows for parameter extrapolation and interpretability.
Gauging a finite subgroup of a global symmetry can map conventional phases and phase transitions to unconventional ones. In this work, we study, as a concrete example, an emergent $\mathbb{Z}_2$-gauged system with global symmetry $U(1)$, namely, the $\mathbb{Z}_2$-gauged Bose-Hubbard model both in 1-D and in 2-D. In certain limits, there is an emergent mixed 't Hooft anomaly between the quotient $\tilde{U}(1)$ symmetry and the dual $\hat{\mathbb{Z}}_2$ symmetry. In 1-D, the superfluid phase is mapped to an intrinsically gapless symmetry-protected topological (SPT) phase, as supported by density-matrix renormalization group (DMRG) calculations. In 2-D, the original superfluid-insulator transition becomes a generalized deconfined quantum critical point (DQCP) between a gapless SPT phase, where a SPT order coexists with Goldstone modes, and a $\tilde{U}(1)$-symmetry-enriched topological (SET) phase. We also discuss the stability of these phases and the critical points to small perturbations and their potential experimental realizations. Our work demonstrates that partial gauging is a simple and yet powerful approach in constructing novel phases and quantum criticalities.
Environmental noise on a controlled quantum system is generally modeled by a dissipative Lindblad equation. This equation describes the average state of the system via the density matrix $\rho$. One way of deriving this Lindblad equation is by introducing a stochastic operator evolving under white noise in the Schr\"odinger equation. However, white noise, where all noise frequencies contribute equally in the power spectral density, is not a realistic noise profile as lower frequencies generally dominate the spectrum. Furthermore, the Lindblad equation does not fully describe the system as a density matrix $\rho$ does not uniquely describe a probabilistic ensemble of pure states $\{\psi_j\}_j$. In this work, we introduce a method for solving for the full distribution of qubit fidelity driven by important stochastic Schr\"odinger equation cases, where qubits evolve under more realistic noise profiles, e.g. Ornstein-Uhlenbeck noise. This allows for predictions of the mean, variance, and higher-order moments of the fidelities of these qubits, which can be of value when deciding on the allowed noise levels for future quantum computing systems, e.g. deciding what quality of control systems to procure. Furthermore, these methods will prove to be integral in the optimal control of qubit states under (classical) control system noise.
The Bose polaron is a quasiparticle that arises from the interaction between impurities and Bogoliubov excitation in Bose-Einstein condensates, analogous to the polaron formed by electrons and phonons in solid-state physics. In this paper, we investigate the effect of phase separation on weakly coupled and strongly coupled Bose polarons. Our findings reveal that phase separation induces a remarkable alteration in the properties of weakly coupled Bose polarons. However, in the case of strong coupling, phase separation cannot destroy the polaron as a highly self-trapping state comes into existence.
The pseudomode framework provides an exact description of the dynamics of an open quantum system coupled to a non-Markovian environment. Using this framework, the influence of the environment on the system is studied in an equivalent model, where the open system is coupled to a finite number of unphysical pseudomodes that follow a time-local master equation. Building on the insight that this master equation does not need to conserve the hermiticity of the pseudomode state, we here ask for the most general conditions on the master equation that guarantee the correct reproduction of the system's original dynamics. We demonstrate that our generalized approach decreases the number of pseudomodes that are required to model, for example, underdamped environments at finite temperature. We also provide an unraveling of the master equation into quantum jump trajectories of non-Hermitian states, which further facilitates the utilization of the pseudomode technique for numerical calculations by enabling the use of easily parallelizable Monte Carlo simulations. Finally, we show that pseudomodes, despite their unphysical nature, provide a natural picture in which physical processes, such as the creation of system-bath correlations or the exchange of heat, can be studied. Hence, our results pave the way for future investigations of the system-environment interaction leading to a better understanding of open quantum systems far from the Markovian weak-coupling limit.
Hong-Ou-Mandel (HOM) interferometry has emerged as a valuable tool for quantum sensing applications, particularly in measuring physical parameters that influence the relative optical delay between pair photons. Unlike classical techniques, HOM-based quantum sensors offer higher resolution due to their intrinsic dispersion cancellation property. Despite this advantage, achieving precise measurements of optical delay crucial for practical applications often involves time-consuming integration and post-processing with traditional statistical methods. To address this challenge, our recent work focused on optimizing optical delay measurements in a time-efficient manner. By carefully selecting the length of a 1 mm periodically-poled KTP (PPKTP) crystal for pair photon generation, we achieved a remarkable group index measurement precision of $\sim 6.75\times 10^{-6}$ per centimeter of sample length, surpassing the previous maximum precision by over 400$\%$. These current measurements maintain fast detection and high photon counts, which are essential for practical quantum sensing applications. The HOM-based method, while limiting the measurement range, can be extended by compensating for photon delay using an optical delay stage. As a proof-of-principle, we measured the group index variation of PPKTP over a temperature range up to 200$^{\circ}$C with a precision in the range of one part per million ($\sim$10$^{-6}$). This advancement not only contributes to quantum sensing but also holds promising implications for high-precision and long-range measurements in quantum optical coherence tomography.
Quantum networks are interconnected by nodes, between singlets which are formed to ensure the successful transmission of information with a probability of 1. However, in real quantum networks, nodes often share a partially entangled state instead of a singlet due to factors such as environmental noise. Therefore, it is necessary to convert the partially entangled state into a singlet for efficient communication. Percolation happens during the conversion of connected edges in the whole network. As a result, when the singlet conversion probability (SCP) is greater than the percolation threshold, a giant interconnected cluster that meets the basic requirements of communication will appear in the network. The percolation threshold of the network reveals the minimum resources required to carry out large scale quantum communication. In this paper, we investigate the effect of different q-swaps on the percolation threshold in quantum entanglement percolation of small world networks. We show that Quantum Entanglement Percolation (QEP) has a better percolation performance than Classical Entanglement Percolation (CEP). By using different q swaps in Watts Strogatz (WS) small world networks and Kleinberg networks for simulation, we also show that the percolation threshold is minimized when SCP is equal to the average degree of the network. Furthermore, we introduce quantum walk as a new scheme to have an extra reduction in the percolation threshold.
The electronic structure problem is one of the main problems in modern theoretical chemistry. While there are many already-established methods both for the problem itself and its applications like semi-classical or quantum dynamics, it remains a computationally demanding task, effectively limiting the size of solved problems. Fortunately, it seems, that offloading some parts of the computation to Quantum Processing Units may offer significant speed-up, often referred to as quantum supremacy or quantum advantage. Together with the potential advantage, this approach simultaneously presents several problems, most notably naturally occurring quantum decoherence, hereafter denoted as quantum noise and lack of large-scale quantum computers, making it necessary to focus on Noisy-Intermediate Scale Quantum computers when developing algorithms aspiring to near-term applications. SA-OO-VQE package aims to answer both these problems with its hybrid quantum-classical conception based on a typical Variational Quantum Eigensolver approach, as only a part of the algorithm utilizes offload to QPUs and the rest is performed on a classical computer, thus partially avoiding both quantum noise and the lack of quantum bits. The SA-OO-VQE has the ability to treat degenerate (or quasi-degenerate) states on the same footing, thus avoiding known numerical optimization problems arising in state-specific approaches around avoided crossings or conical intersections.
Since quantum spatial searches on complex networks have a strong network dependence, the question arises whether the universal perspective exists in this quantum algorithm for complex networks. Here, we uncover the universal scaling laws of the quantum spatial search on complex networks such as small-world and scale-free networks. The average path length, a key quantity in the complex network science, is useful to expose this universal feature, where the collapse plot can be generated for the optimal time, the maximal finding probability and the optimal hopping parameter. Based on the path integral method, we also clarify that the probability amplitude in the continuous-time quantum walk can be determined by the path length distribution. Our results demonstrate a new link between the quantum physics and the complex networks.
The state of an open quantum system undergoing an adiabatic process evolves by following the instantaneous stationary state of its time-dependent generator. This observation allows one to characterize, for a generic adiabatic evolution, the average dynamics of the open system. However, information about fluctuations of dynamical observables, such as the number of photons emitted or the time-integrated stochastic entropy production in single experimental runs, requires controlling the whole spectrum of the generator and not only the stationary state. Here, we show how such information can be obtained in adiabatic open quantum dynamics by exploiting tools from large deviation theory. We prove an adiabatic theorem for deformed generators, which allows us to encode, in a biased quantum state, the full counting statistics of generic time-integrated dynamical observables. We further compute the probability associated with an arbitrary "rare" time-history of the observable and derive a dynamics which realizes it in its typical behavior. Our results provide a way to characterize and engineer adiabatic open quantum dynamics and to control their fluctuations.
This paper delves into the significance of the tomographic probability density function (pdf) representation of quantum states, shedding light on the special classes of pdfs that can be tomograms. Instead of using wave functions or density operators on Hilbert spaces, tomograms, which are the true pdfs, are used to completely describe the states of quantum systems. Unlike quasi-pdfs, like the Wigner function, tomograms can be analysed using all the tools of classical probability theory for pdf estimation, which can allow a better quality of state reconstruction. This is particularly useful when dealing with non-Gaussian states where the pdfs are multi-mode. The knowledge of the family of distributions plays an important role in the application of both parametric and non-parametric density estimation methods. We show that not all pdfs can play the role of tomograms of quantum states and introduce the conditions that must be fulfilled by pdfs to be "quantum".
In this article, we establish a mathematical framework that utilizes concepts from graph theory to define the parity transformation as a mapping that encompasses all possible compiled hypergraphs, and investigate uniqueness properties of this mapping in more detail. By introducing so-called loop labelings, we derive an alternative expression of the preimage of any set of compiled hypergraphs under this encoding procedure when all equivalences classes of graphs are being considered. We then deduce equivalent conditions for the injectivity of the parity transformation on any subset of all equivalences classes of graphs. Moreover, we show concrete examples of optimization problems demonstrating that the parity transformation is not an injective mapping, and also introduce an important class of plaquette layouts and their corresponding set of constraints whose preimage is uniquely determined. In addition, we provide an algorithm which is based on classical algorithms from theoretical computer science and computes a compiled physical layout in this class in polynomial time.
We present an easily reproducible inexpensive microwave antenna that can generate a strong and homogeneous magnetic field of arbitrary polarization, which enables fast and coherent control of electron spins over a large volume. Unlike preceding works, we present a resonant antenna that maintains its resonant behaviour regardless of the proximity of other experimental hardware components. This robustness is crucial as it enables, amongst others, using microscope objectives with short working distances to perform wide field imaging/sensing with bulk diamonds. The antenna generates a magnetic field strength of 22.3 A/m for 1 W total driving power, which doubles the power efficiency compared with previously reported patch antenna designs. The magnetic field homogeneity in a volume of $1 \text{mm}^3$ is within 6.6\%. The antenna has a full width at half maximum bandwidth of $\sim$160 MHz and its resonant frequency can be tuned over a 400 MHz range via four capacitors or varactors. The antenna has been tested and found to remain within safe handling temperatures during continuous-wave operation at 8 W. The files required to reproduce this antenna, which can be built on a standard and affordable double sided PCB, are provided open-source. This work facilitates a robust and versatile piece of instrumentation, being particularly appealing for applications such as high sensitivity magnetometry and wide field imaging/sensing with Nitrogen Vacancy centers.
Stabilizer channels, which are stabilizer circuits that implement logical operations while mapping from an input stabilizer code to an output stabilizer code, are ubiquitous for fault tolerant quantum computing not just with surface codes, but with general LDPC codes and Floquet codes. We introduce a rigorous and general formalism to analyze the fault tolerance properties of any stabilizer channel under a broad class of noise models. We provide rigorous but easy-to-work-with definitions and algorithms for the fault distance and hook faults for stabilizer channels. Additionally, we establish necessary conditions such that channel composition preserves the fault distance. We apply our framework to design and analyze fault tolerant stabilizer channels for surface codes, revealing novel aspects of fault tolerant circuits.
Certifying whether an arbitrary quantum system is entangled or not, is, in general, an NP-hard problem. Though various necessary and sufficient conditions have already been explored in this regard for lower dimensional systems, it is hard to extend them to higher dimensions. Recently, an ensemble bagging and convex hull approximation (CHA) approach (together, BCHA) was proposed and it strongly suggests employing a machine learning technique for the separability-entanglement classification problem. However, BCHA does only incorporate the balanced dataset for classification tasks which results in lower average accuracy. In order to solve the data imbalance problem in the present literature, an exploration of the Boosting technique has been carried out, and a trade-off between the Boosting and Bagging-based ensemble classifier is explored for quantum separability problems. For the two-qubit and two-qutrit quantum systems, the pros and cons of the proposed random under-sampling boost CHA (RUSBCHA) for the quantum separability problem are compared with the state-of-the-art CHA and BCHA approaches. As the data is highly unbalanced, performance measures such as overall accuracy, average accuracy, F-measure, and G-mean are evaluated for a fair comparison. The outcomes suggest that RUSBCHA is an alternative to the BCHA approach. Also, for several cases, performance improvements are observed for RUSBCHA since the data is imbalanced.
A backward wave optical parametric oscillator (BWOPO) waveguide in periodically poled Rb-doped KTP is presented. The waveguide exhibits low loss (0.16 dB/cm) and has an oscillation threshold, almost 20 times lower than the corresponding bulk device. The backward wave has a narrow linewidth of 21 GHz at 1514.6 nm while the forward wave at 1688.7 nm has a spectrum replicating the pump. The unique spectral features of the BWOPO will unlock novel opportunities in low-power nonlinear integrated optics. A conversion efficiency of 8.4% was obtained limited by the emergence of backward stimulated polariton scattering.
Advancements in classical computing have significantly enhanced machine learning applications, yet inherent limitations persist in terms of energy, resource and speed. Quantum machine learning algorithms offer a promising avenue to overcome these limitations but bring along their own challenges. This experimental study explores the limits of trainability of a real experimental quantum classical hybrid system implementing supervised training protocols, in an ion trap platform. Challenges associated with ion trap-coupled classical processor are addressed, highlighting the robustness of the genetic algorithm as a classical optimizer in navigating complex optimization landscape inherent in binary classification problems with many local minima. Experimental results, focused on a binary classification problem, reveal the superior efficiency and accuracy of the genetic algorithm compared to gradient-based optimizers. We intricately discuss why gradient-based optimizers may not be suitable in the NISQ era through thorough analysis. These findings contribute insights into the performance of quantum-classical hybrid systems, emphasizing the significance of efficient training strategies and hardware considerations for practical quantum machine learning applications. This work not only advances the understanding of hybrid quantum-classical systems but also underscores the potential impact on real-world challenges through the convergence of quantum and classical computing paradigms operating without the aid of classical simulators.
The eigenvalue problem, a cornerstone in linear algebra, provides profound insights into studying matrix properties. Quantum algorithms addressing this problem have hitherto been constrained to special normal matrices assuming spectral decomposition, leaving the extension to general matrices an open challenge. In this work, we present a novel family of quantum algorithms tailored for solving the eigenvalue problem for general matrices, encompassing scenarios with complex eigenvalues or even defective matrices. Our approach begins by tackling the task of searching for an eigenvalue without additional constraints. For diagonalizable matrices, our algorithm has $\tilde O(\varepsilon^{-1})$ complexity with an error $\varepsilon$, achieving the nearly Heisenberg scaling. Subsequently, we study the identification of eigenvalues closest to a specified point or line, extending the results for ground energy and energy gap problems in Hermitian matrices. We achieve an accuracy scaling of $\tilde O(\varepsilon^{-2})$ for general diagonalizable matrices, further refining to $\tilde O(\varepsilon^{-1})$ under the condition of real eigenvalues or constant distance from the reference point. The algorithm's foundation lies in the synergy of three techniques: the relationship between eigenvalues of matrix $A$ and the minimum singular value of $A-\mu I$, quantum singular value threshold subroutine extended from quantum singular-value estimation, and problem-specific searching algorithms. Our algorithms find applications in diverse domains, including estimating the relaxation time of Markov chains, solving Liouvillian gaps in open quantum systems, and verifying PT-symmetry broken/unbroken phases. These applications underscore the significance of our quantum eigensolvers for problems across various disciplines.
The extension of the Rayleigh-Ritz variational principle to ensemble states $\rho_{\mathbf{w}}\equiv\sum_k w_k |\Psi_k\rangle \langle\Psi_k|$ with fixed weights $w_k$ lies ultimately at the heart of several recent methodological developments for targeting excitation energies by variational means. Prominent examples are density and density matrix functional theory, Monte Carlo sampling, state-average complete active space self-consistent field methods and variational quantum eigensolvers. In order to provide a sound basis for all these methods and to improve their current implementations, we prove the validity of the underlying critical hypothesis: Whenever the ensemble energy is well-converged, the same holds true for the ensemble state $\rho_{\mathbf{w}}$ as well as the individual eigenstates $|\Psi_k\rangle$ and eigenenergies $E_k$. To be more specific, we derive linear bounds $d_-\Delta{E}_{\mathbf{w}} \leq \Delta Q \leq d_+ \Delta\Delta{E}_{\mathbf{w}}$ on the errors $\Delta Q $ of these sought-after quantities. A subsequent analytical analysis and numerical illustration proves the tightness of our universal inequalities. Our results and particularly the explicit form of $d_{\pm}\equiv d_{\pm}^{(Q)}(\mathbf{w},\mathbf{E})$ provide valuable insights into the optimal choice of the auxiliary weights $w_k$ in practical applications.
We investigate the role of magic in the quantum capacity of channels. We consider the quantum channel of the recently proposed discrete beam splitter with the fixed environment state. We find that if the fixed environment state is a stabilizer state, then the quantum capacity is zero. Moreover, we find that the quantum capacity is nonzero for some magic states, and the quantum capacity increases linearly with respect to the number of single-qudit magic states in the environment. These results suggest that magic can increase the quantum capacity of channels, which sheds new insight into the role of stabilizer and magic states in quantum communication.
Superconducting circuits reveal themselves as promising physical devices with multiple uses. Within those uses, the fundamental concept of the geometric phase accumulated by the state of a system shows up recurrently, as, for example, in the construction of geometric gates. Given this framework, we study the geometric phases acquired by a paradigmatic setup: a transmon coupled to a superconductor resonating cavity. We do so both for the case in which the evolution is unitary and when it is subjected to dissipative effects. These models offer a comprehensive quantum description of an anharmonic system interacting with a single mode of the electromagnetic field within a perfect or dissipative cavity, respectively. In the dissipative model, the non-unitary effects arise from dephasing, relaxation, and decay of the transmon coupled to its environment. Our approach enables a comparison of the geometric phases obtained in these models, leading to a thorough understanding of the corrections introduced by the presence of the environment.
Abstract Simulating mixed-state evolution in open quantum systems is crucial for various chemical physics, quantum optics, and computer science applications. These simulations typically follow the Lindblad master equation dynamics. An alternative approach known as quantum state diffusion unraveling is based on the trajectories of pure states generated by random wave functions, which evolve according to a nonlinear It\^o-Schr\"odinger equation (ISE). This study introduces weak first- and second-order solvers for the ISE based on directly applying the It\^o-Taylor expansion with exact derivatives in the interaction picture. We tested the method on free and driven Morse oscillators coupled to a thermal environment and found that both orders allowed practical estimation with a few dozen iterations. The variance was relatively small compared to the linear unraveling and did not grow with time. The second-order solver delivers much higher accuracy and stability with bigger time steps than the first-order scheme, with a small additional workload. However, the second-order algorithm has quadratic complexity with the number of Lindblad operators as opposed to the linear complexity of the first-order algorithm.
Boltzmann's constant reflects a historical misunderstanding of the concept of entropy, whose informational nature is obfuscated when expressed in J/K. We suggest that the development of temperature and energy, historically prior to that of entropy, does not amount to their logical priority: Temperature should be defined in terms of entropy, not vice versa. Following the precepts of information theory, entropy is measured in bits, and coincides with information capacity at thermodynamic equilibrium. Consequently, not only is the temperature of an equilibrated system expressed in J/bit, but it acquires an operational meaning: It is the cost in energy to increase its information capacity by 1 bit. Our proposal also supports the notion of available capacity, analogous to free energy. Finally, it simplifies Landauer's cost and clarifies that it is a cost of displacement, not of erasure.
The Coherent Ising Machine (CIM) is a non-conventional architecture that takes inspiration from physical annealing processes to solve Ising problems heuristically. Its dynamics are naturally continuous and described by a set of ordinary differential equations that have been proven to be useful for the optimization of continuous variables non-convex quadratic optimization problems. The dynamics of such Continuous Variable CIMs (CV-CIM) encourage optimization via optical pulses whose amplitudes are determined by the negative gradient of the objective; however, standard gradient descent is known to be trapped by local minima and hampered by poor problem conditioning. In this work, we propose to modify the CV-CIM dynamics using more sophisticated pulse injections based on tried-and-true optimization techniques such as momentum and Adam. Through numerical experiments, we show that the momentum and Adam updates can significantly speed up the CV-CIM's convergence and improve sample diversity over the original CV-CIM dynamics. We also find that the Adam-CV-CIM's performance is more stable as a function of feedback strength, especially on poorly conditioned instances, resulting in an algorithm that is more robust, reliable, and easily tunable. More broadly, we identify the CIM dynamical framework as a fertile opportunity for exploring the intersection of classical optimization and modern analog computing.
We report observations of discrete charge states of a coherent dielectric two-level system (TLS) that is strongly coupled to an offset-charge-sensitive superconducting transmon qubit. We measure an offset charge of 0.072$e$ associated with the two TLS eigenstates, which have a transition frequency of 2.9 GHz and a relaxation time exceeding 3 ms. Combining measurements in the strong dispersive and resonant regime, we quantify both transverse and longitudinal couplings of the TLS-qubit interaction. We further perform joint tracking of TLS transitions and quasiparticle tunneling dynamics but find no intrinsic correlations. This study demonstrates microwave-frequency TLS as a source of low-frequency charge noise.
We report on the current development of a single photon source based on a long-range interacting room temperature rubidium vapor. We discuss the history of the project, the production of vapor cells, and the observation of Rabi-oscillations in the four-wave-mixing excitation scheme.
In this work we strictly and accurately (within standard quantum mechanical formalism) consider basic part of any single photon interference experiment. Namely we consider quantum dynamical interaction between single photon and photographic plate (for photon described by superposition or by statistical mixture of two quantum trajectories or when single photon is entangled with some other quantum system (photon trajectories detector)). Moreover we consider basic problem of the quantum mechanics foundation, problem of the transition (collapse) from quantum superposition or entanglement in statistical mixture of quantum states. Also we use model of the collapse according to which collapse represents a quantum-classical continuous phase transition with spontaneous (non-dynamical) unitary symmetry (superposition) breaking (effective hiding). (Practically, collapse can be considered as an especial case of the general formalism of spontaneous symmetry breaking that can be successfully applied in many different domains of the physics.) All this (that can be simply generalized for arbitrary quantum system) is in full agreement with existing experimental facts. More over it admits existence of the entanglement between photon (quantum system) and detector (Schrodinger cat effect) which clearly demonstrates that detection procedure (collapse) has no any absolute character. It admits a simple solution of the quantum mechanics foundation problem.
The relationship between expectation and price is commonly established with two principles: no-arbitrage, which asserts that both maps are positive; and equivalence, which asserts that the maps share the same null events. Constructed from the Arrow-Debreu securities, classical and quantum models of economics are then distinguished by their respective use of classical and quantum logic, following the program of von Neumann. In this essay, the operations and axioms of quantum groups are discovered in the minimal preconditions of stochastic and functional calculus, making this the natural domain for the axiomatic development of mathematical finance. Quantum economics emerges from the twin pillars of the Gelfand-Naimark-Segal construction, implementing the principle of no-arbitrage, and the Radon-Nikodym theorem, implementing the principle of equivalence. Exploiting quantum group duality, a holographic principle that exchanges the roles of state and observable creates two distinct economic models from the same set of elementary valuations. Advocating on the grounds that this contains and extends classical economics, noncommutativity is presented as a modelling resource, with novel applications in the pricing of options and other derivative securities.
We present several inequalities related to the Robertson-Schr\"odinger uncertainty relation. In all these inequalities, we consider a decomposition of the density matrix into a mixture of states, and use the fact that the Robertson-Schr\"odinger uncertainty relation is valid for all these components. By considering a convex roof of the bound, we obtain an alternative derivation of the relation in Fr\"owis et al. [Phys. Rev. A 92, 012102 (2015)], and we can also list a number of conditions that are needed to saturate the relation. We present a formulation of the Cram\'er-Rao bound involving the convex roof of the variance. By considering a concave roof of the bound in the Robertson-Schr\"odinger uncertainty relation over decompositions to mixed states, we obtain an improvement of the Robertson-Schr\"odinger uncertainty relation. We consider similar techniques for uncertainty relations with three variances. Finally, we present further uncertainty relations that provide lower bounds on the metrological usefulness of bipartite quantum states based on the variances of the canonical position and momentum operators for two-mode continuous variable systems. We show that the violation of well-known entanglement conditions in these systems discussed in Duan et al., [Phys. Rev. Lett. 84, 2722 (2000)] and Simon [Phys. Rev. Lett. 84, 2726 (2000)] implies that the state is more useful metrologically than certain relevant subsets of separable states. We present similar results concerning entanglement conditions with angular momentum operators for spin systems.
We consider an analogue of the well-known Riemann Hypothesis based on quantum walks on graphs with the help of the Konno-Sato theorem. Furthermore, we give some examples for complete, cycle, and star graphs.
Quantum communication networks (QCNs) utilize quantum mechanics for secure information transmission, but the reliance on fragile and expensive photonic quantum resources renders QCN resource optimization challenging. Unlike prior QCN works that relied on blindly compressing direct quantum embeddings of classical data, this letter proposes a novel quantum semantic communications (QSC) framework exploiting advancements in quantum machine learning and quantum semantic representations to extracts and embed only the relevant information from classical data into minimal high-dimensional quantum states that are accurately communicated over quantum channels with quantum communication and semantic fidelity measures. Simulation results indicate that, compared to semantic-agnostic QCN schemes, the proposed framework achieves approximately 50-75% reduction in quantum communication resources needed, while achieving a higher quantum semantic fidelity.
Near-term quantum computers have been built as intermediate-scale quantum devices and are fragile against quantum noise effects, namely, NISQ devices. Traditional quantum-error-correcting codes are not implemented on such devices and to perform quantum computation in good accuracy with these machines we need to develop alternative approaches for mitigating quantum computational errors. In this work, we propose quantum error mitigation (QEM) scheme for quantum computational errors which occur due to couplings with environments during gate operations, i.e., decoherence. To establish our QEM scheme, first we estimate the quantum noise effects on single-qubit states and represent them as groups of quantum circuits, namely, quantum-noise-effect circuit groups. Then our QEM scheme is conducted by subtracting expectation values generated by the quantum-noise-effect circuit groups from that obtained by the quantum circuits for the quantum algorithms under consideration. As a result, the quantum noise effects are reduced, and we obtain approximately the ideal expectation values via the quantum-noise-effect circuit groups and the numbers of elementary quantum circuits composing them scale polynomial with respect to the products of the depths of quantum algorithms and the numbers of register bits. To numerically demonstrate the validity of our QEM scheme, we run noisy quantum simulations of qubits under amplitude damping effects for four types of quantum algorithms. Furthermore, we implement our QEM scheme on IBM Q Experience processors and examine its efficacy. Consequently, the validity of our scheme is verified via both the quantum simulations and the quantum computations on the real quantum devices.
The max-relative entropy and the conditional min-entropy it induces have become central to one-shot information theory. Both may be expressed in terms of a conic program over the positive semidefinite cone. Recently, it was shown that the same conic program altered to be over the separable cone admits an operational interpretation in terms of communicating classical information over a quantum channel. In this work, we generalize this framework of replacing the cone to determine which results in quantum information theory rely upon the positive semidefinite cone and which can be generalized. We show the fully quantum Stein's lemma and asymptotic equipartition property break down if the cone exponentially increases in resourcefulness but never approximates the positive semidefinite cone. However, we show for CQ states, the separable cone is sufficient to recover the asymptotic theory, thereby drawing a strong distinction between the fully and partial quantum settings. We present parallel results for the extended conditional min-entropy. In doing so, we extend the notion of k-superpositive channels to superchannels. We also present operational uses of this framework. We first show the cone restricted min-entropy of a Choi operator captures a measure of entanglement-assisted noiseless classical communication using restricted measurements. We show that quantum majorization results naturally generalize to other cones. As a novel example, we introduce a new min-entropy-like quantity that captures the quantum majorization of quantum channels in terms of bistochastic pre-processing. Lastly, we relate this framework to general conic norms and their non-additivity. Throughout this work we emphasize the introduced measures' relationship to general convex resource theories. In particular, we look at both resource theories that capture locality and resource theories of coherence/Abelian symmetries.
High-dimensional entanglement has been identified as an important resource in quantum information processing, and also as a main obstacle for simulating quantum systems. Its certification is often difficult, and most widely used methods for experiments are based on fidelity measurements with respect to highly entangled states. Here, instead, we consider covariances of collective observables, as in the well-known Covariance Matrix Criterion (CMC)[1] and present a generalization of the CMC for determining the Schmidt number of a bipartite system. This is potentially particularly advantageous in many-body systems, such as cold atoms, where the set of practical measurements is very limited and only variances of collective operators can typically be estimated. To show the practical relevance of our results, we derive simpler Schmidt-number criteria that require similar information as the fidelity-based witnesses, yet can detect a wider set of states. We also consider paradigmatic criteria based on spin covariances, which would be very helpful for experimental detection of high-dimensional entanglement in cold atom systems. We conclude by discussing the applicability of our results to a multiparticle ensemble and some open questions for future work.
The purpose of the present paper is to discuss the time dependent Schr\"odinger equation on a metric graph with time-dependent edge lengths, and the proper way to pose the problem so that the corresponding time evolution is unitary. We show that the well posedness of the Schr\"odinger equation can be guaranteed by replacing the standard Kirchhoff Laplacian with a magnetic Schr\"odinger operator with a harmonic potential. We then generalize the result to time dependent families of vertex conditions. We also apply the theory to show the existence of a geometric phase associated with a slowly changing quantum graph.
We construct a lower bound of the tensor rank for a new class of tensors, which we call persistent tensors. We present three specific families of persistent tensors, of which the lower bound is tight. We show that there is a chain of degenerations between these three families of minimal-rank persistent tensors that can be used to study the entanglement transformation between them. In addition, we show that these three families of persistent tensors are indeed different generalizations of multiqubit $\rm{W}$ states within multiqudit systems and are geometrically in the orbit closure of multiqudit $\rm{GHZ}$ states. Consequently, we show that one can obtain every one of the generalizations of $\rm{W}$ state from a multiqudit $\rm{GHZ}$ state via asymptotic Stochastic Local Operations and Classical Communication (SLOCC) with rate one. Finally, we extend the obtained lower bound of the tensor rank to direct sums with persistent summands and to even more general combinations of tensors, which we call block pyramidal tensors. As a result, we show that the tensor rank is multiplicative under the Kronecker and tensor products of minimal-rank persistent tensors with the $\rm{GHZ}$ tensor.
Because of the probabilistic/nondeterministic behavior of quantum programs, it is highly advisable to verify them formally to ensure that they correctly implement their specifications. Formal verification, however, also traditionally requires significant effort. To address this challenge, we present Qafny, an automated proof system based on the program verifier Dafny and designed for verifying quantum programs. At its core, Qafny uses a type-guided quantum proof system that translates quantum operations to classical array operations modeled within a classical separation logic framework. We prove the soundness and completeness of our proof system and implement a prototype compiler that transforms Qafny programs and specifications into Dafny for automated verification purposes. We then illustrate the utility of Qafny's automated capabilities in efficiently verifying important quantum algorithms, including quantum-walk algorithms, Grover's algorithm, and Shor's algorithm.
We provide in this paper a concrete method for training a quantum neural network to maximize the relevant information about a property that is transmitted through the network. This is significant because it gives an operationally well founded quantity to optimize when training autoencoders for problems where the inputs and outputs are fully quantum. We provide a rigorous algorithm for computing the value of the quantum information bottleneck quantity within error $\epsilon$ that requires $O(\log^2(1/\epsilon) + 1/\delta^2)$ queries to a purification of the input density operator if its spectrum is supported on $\{0\}~\bigcup ~[\delta,1-\delta]$ for $\delta>0$ and the kernels of the relevant density matrices are disjoint. We further provide algorithms for estimating the derivatives of the QIB function, showing that quantum neural networks can be trained efficiently using the QIB quantity given that the number of gradient steps required is polynomial.
Projective quantum measurement is a theoretically accepted process in modern quantum mechanics. However, its projection hypothesis is widely regarded as an experimentally established empirical law. In this paper, we combine a previous result regarding the realization of a Hamiltonian process of the projection hypothesis in projective quantum measurement, where the complete set of the orbital observables of the center of mass of a macroscopic quantum mechanical system is restricted to a set of mutually commuting classical observables, and a previous result regarding the work required for an event reading (i.e., the informatical process in projective quantum measurement). Then, a quantum thermodynamic scheme is proposed for experimentally testing these two mutually independent theoretical results of projective quantum measurement simultaneously.
Gravity differs from all other known fundamental forces since it is best described as a curvature of spacetime. For that reason it remains resistant to unifications with quantum theory. Gravitational interaction is fundamentally weak and becomes prominent only at macroscopic scales. This means, we do not know what happens to gravity in the microscopic regime where quantum effects dominate, and whether quantum coherent effects of gravity become apparent. Levitated mechanical systems of mesoscopic size offer a probe of gravity, while still allowing quantum control over their motional state. This regime opens the possibility of table-top testing of quantum superposition and entanglement in gravitating systems. Here we show gravitational coupling between a levitated sub-millimeter scale magnetic particle inside a type-I superconducting trap and kg source masses, placed approximately half a meter away. Our results extend gravity measurements to low gravitational forces of attonewton and underline the importance of levitated mechanical sensors. Specifically, at a frequency of 26.7 Hz, a mass of 0.4 mg and showing Q-factors in excess of 10$^7$, we obtained a force noise of 0.5 $fN\sqrt{Hz}$ . We simultaneously detect the other 5 rotational and translational degrees of freedom.
This paper explores the sensitivity of the human visual system to the quantum entangled photons. We examine the possibility of human subjects perceiving multi-photon entangled state through psychophysical experiments. Our focus begins with a two-photon entangled state to make a comparative study with the literature by taking into account additive noise for false positive on two-photon entanglement perception by humans. After that, we limit our similar investigation to a three-photon entangled state for simplicity in higher dimensions. To model the photodetection by humans, we employ the probability of seeing determined for coherently amplified photons in Fock number states, including an additive noise. Our results indicate that detecting two-photon and three-photon entanglement with the human eye is possible for a certain range of additive noise levels and visual thresholds. Finally, we discuss several alternative amplification methods.
The question of what makes a data distribution suitable for deep learning is a fundamental open problem. Focusing on locally connected neural networks (a prevalent family of architectures that includes convolutional and recurrent neural networks as well as local self-attention models), we address this problem by adopting theoretical tools from quantum physics. Our main theoretical result states that a certain locally connected neural network is capable of accurate prediction over a data distribution if and only if the data distribution admits low quantum entanglement under certain canonical partitions of features. As a practical application of this result, we derive a preprocessing method for enhancing the suitability of a data distribution to locally connected neural networks. Experiments with widespread models over various datasets demonstrate our findings. We hope that our use of quantum entanglement will encourage further adoption of tools from physics for formally reasoning about the relation between deep learning and real-world data.
We present a novel inequality on the purity of a bipartite state depending solely on the difference of the local Bloch vector lengths. For two qubits this inequality is tight for all marginal states and so extends the previously known solution for the 2-qubit marginal problem and opens a new research avenue. We further use this inequality to construct a 3-dimensional Bloch model of the 2-qubit quantum state space in terms of Bloch lengths, thus providing a geometrically pleasing visualization of this difficult to access high-dimensional state space. This allows to characterize quantum states relying on a strongly reduced set of parameters alone and to investigate the interplay between local properties of the marginal systems and global properties encoded in the correlations.
Kerr-cat qubits are a promising candidate for fault-tolerant quantum computers owing to the biased nature of their errors. The $ZZ$ coupling between the qubits can be utilized for a two-qubit entangling gate, but the residual coupling called $ZZ$ crosstalk is detrimental to precise computing. In order to resolve this problem, we propose a tunable $ZZ$-coupling scheme using two transmon couplers. By setting the detunings of the two couplers at opposite values, the residual $ZZ$ couplings via the two couplers cancel each other out. We also apply our scheme to the $R_{zz}(\Theta)$ gate ($ZZ$ rotation with angle $\Theta$), one of the two-qubit entangling gates. We numerically show that the fidelity of the $R_{zz}(-\pi/2)$ gate is higher than 99.9% in a case of $16$-ns gate time and without decoherence.
Chirality in integrated quantum photonics has emerged as a promising route towards achieving scalable quantum technologies with quantum nonlinearity effects. Topological photonic waveguides, which utilize helical optical modes, have been proposed as a novel approach to harnessing chiral light-matter interactions on-chip. However, uncertainties remain regarding the nature and strength of the chiral coupling to embedded quantum emitters, hindering the scalability of these systems. In this work, we present a comprehensive investigation of chiral coupling in topological photonic waveguides using a combination of experimental, theoretical, and numerical analyses. We quantitatively characterize the position-dependence nature of the light-matter coupling on several topological photonic waveguides and benchmark their chiral coupling performance against conventional line defect waveguides for chiral quantum optical applications. Our results provide crucial insights into the degree and characteristics of chiral light-matter interactions in topological photonic quantum circuits and pave the way towards the implementation of quantitatively-predicted quantum nonlinear effects on-chip.
Despite recent intensive research on topological aspects of open quantum systems, effects of strong interactions have not been sufficiently explored. In this paper, we demonstrate that complex-valued interactions induce the Liouvillian skin effect by analyzing a one-dimensional correlated model with two-body loss. We show that, in the presence of complex-valued interactions, eigenmodes and eigenvalues of the Liouvillian strongly depend on boundary conditions. Specifically, we find that complex-valued interactions induce localization of eigenmodes of the Liouvillian around the right edge under open boundary conditions. To characterize the Liouvllian skin effect, we define the topological invariant by using the Liouvillian superoperator. Then, we numerically confirm that the topological invariant captures the Liouvillian skin effect. Furthermore, the presence of the localization of eigenmodes results in the unique dynamics observed only under open boundary conditions: particle accumulation at the right edge in transient dynamics. Our result paves the way to realize topological phenomena in open quantum systems induced by strong interactions.
We present the white paper developed during the QEYSSat 2.0 study, which was undertaken between June 2021 and March 2022. The study objective was to establish a technology road-map for a Canada-wide quantum network enabled by satellites. We survey the state-of-art in quantum communication technologies, identify the main applications and architectures, review the technical readiness levels and technology bottlenecks and identify a future mission scenario. We report the findings of a dedicated one-day workshop that included Canadian stakeholders from government, industry and academia to gather inputs and insights for the applications and technical road-map. We also provide an overview of the Quantum EncrYption and Science Satellite (QEYSSat) mission expected to launch in 2024-2025 and its anticipated outcomes. One of the main outcomes of this study is that developing the main elements for a Canada-wide quantum internet will have the highest level of impact, which includes Canada-wide entanglement distribution and teleportation. We present and analyze a possible future mission ('QEYSSat 2.0') that would enable a long range quantum teleportation across Canada as an important step towards this vision.
We show that the second law of thermodynamics poses a restriction on how well we can discriminate between quantum states. By examining an ideal gas with a quantum internal degree of freedom undergoing a cycle based on a proposal by Asher Peres, we establish a non-trivial upper bound on the attainable accuracy of quantum state discrimination. This thermodynamic bound, which relies solely on the linearity of quantum mechanics and the constraint of no work extraction, matches Holevo's bound on accessible information, but is looser than the Holevo-Helstrom bound. The result gives more evidence on the disagreement between thermodynamic entropy and von Neumann entropy, and places potential limitations on proposals beyond quantum mechanics.
Complementarity is a cornerstone of quantum theory, assisting in the analysis and understanding of various quantum phenomena. This concept has even been assumed in theoretical studies in relativistic regimes. Here, we conduct a study of two generalized delayed-choice interferometers traveled by a system with an internal spin. We show how a complete complementarity relation can be indeed applied in these two setups and how the trade-off between the quantities in this relation, namely, path coherence, von Neumann predictability, and entropy of entanglement, is affected by special and general time dilation in an arbitrary spacetime. These modifications originate from Wigner rotations, which couple the spin to the external degrees of freedom of the system and do not rely on the spin acting as a clock. Despite having different complementarity trade-offs, both arrangements have the same interferometric visibility, as we unveil. To give a concrete example, we analyze the Newtonian limit of these results.
The reconstruction of quantum states from experimental measurements, often achieved using quantum state tomography (QST), is crucial for the verification and benchmarking of quantum devices. However, performing QST for a generic unstructured quantum state requires an enormous number of state copies that grows \emph{exponentially} with the number of individual quanta in the system, even for the most optimal measurement settings. Fortunately, many physical quantum states, such as states generated by noisy, intermediate-scale quantum computers, are usually structured. In one dimension, such states are expected to be well approximated by matrix product operators (MPOs) with a finite matrix/bond dimension independent of the number of qubits, therefore enabling efficient state representation. Nevertheless, it is still unclear whether efficient QST can be performed for these states in general. In this paper, we attempt to bridge this gap and establish theoretical guarantees for the stable recovery of MPOs using tools from compressive sensing and the theory of empirical processes. We begin by studying two types of random measurement settings: Gaussian measurements and Haar random rank-one Positive Operator Valued Measures (POVMs). We show that the information contained in an MPO with a finite bond dimension can be preserved using a number of random measurements that depends only \emph{linearly} on the number of qubits, assuming no statistical error of the measurements. We then study MPO-based QST with physical quantum measurements through Haar random rank-one POVMs that can be implemented on quantum computers. We prove that only a \emph{polynomial} number of state copies in the number of qubits is required to guarantee bounded recovery error of an MPO state.
We investigate the influence of geometry on the preservation of quantum coherence in spin clusters subjected to a thermal environment. Assuming weak inter-spin coupling, we explore the various buffer network configurations that can be embedded in a plane. Our findings reveal that the connectivity of the buffer network is crucial in determining the preservation duration of quantum coherence in an individual central spin. Specifically, we observe that the maximal planar graph yields the longest preservation time for a given number of buffer spins. Interestingly, our results demonstrate that the preservation time does not consistently increase with an increasing number of buffer spins. Employing a quantum master equation in our simulations, we further demonstrate that a tetrahedral geometry comprising a four-spin buffer network provides optimal protection against environmental effects.
The objective of the present paper is the study of a one-dimensional Hamiltonian with the interaction term given by the sum of two nonlocal attractive $\delta'$-interactions of equal strength and symmetrically located with respect to the origin. We use the procedure known as {\it renormalisation of the coupling constant} in order to rigorously achieve a self-adjoint determination for this Hamiltonian. This model depends on two parameters, the interaction strength and the distance between the centre of each interaction and the origin. Once we have the self-adjoint determination, we obtain its discrete spectrum showing that it consists of two negative eigenvalues representing the energy levels. We analyse the dependence of these energy levels on the above-mentioned parameters. We investigate the possible resonances of the model. Furthermore, we analyse in detail the limit of our model as the distance between the supports of the two $\delta'$ interactions vanishes.
We show that constraints imposed by strong Hilbert space fragmentation (HSF) along with the presence of certain global symmetries can ensure the reality of eigenspectra of non-Hermitian quantum systems; such a reality cannot be guaranteed by global symmetries alone. We demonstrate this insight for two interacting finite chains, namely the fermionic Nelson-Hatano and the Su-Schrieffer-Heeger models, none of which has a $\mathcal{PT}$ symmetry. We show analytically that strong HSF and real spectrum are both consequences of the same dynamical constraints in the limit of large interaction, provided the systems have sufficient global symmetries. We also show that a local equal-time correlation function can detect the many-body exceptional point at a finite critical interaction strength above which the eigenspectrum is real.
Dicke states are completely symmetric states of multiple qubits (2-level systems), and qudit Dicke states are their $d$-level generalization. We define here $q$-deformed qudit Dicke states using the quantum algebra $su_q(d)$. We show that these states can be compactly expressed as a weighted sum over permutations with $q$-factors involving the so-called inversion number, an important permutation statistic in Combinatorics. We use this result to compute the bipartite entanglement entropy of these states. We also discuss the preparation of these states on a quantum computer, and show that introducing a $q$-dependence does not change the circuit gate count.
The random sampling task performed by Google's Sycamore processor gave us a glimpse of the "Quantum Supremacy era". This has definitely shed some spotlight on the power of random quantum circuits in this abstract task of sampling outputs from the (pseudo-) random circuits. In this manuscript, we explore a practical near-term use of local random quantum circuits in dimensional reduction of large low-rank data sets. We make use of the well-studied dimensionality reduction technique called the random projection method. This method has been extensively used in various applications such as image processing, logistic regression, entropy computation of low-rank matrices, etc. We prove that the matrix representations of local random quantum circuits with sufficiently shorter depths ($\sim O(n)$) serve as good candidates for random projection. We demonstrate numerically that their projection abilities are not far off from the computationally expensive classical principal components analysis on MNIST and CIFAR-100 image data sets. We also benchmark the performance of quantum random projection against the commonly used classical random projection in the tasks of dimensionality reduction of image datasets and computing Von Neumann entropies of large low-rank density matrices. And finally using variational quantum singular value decomposition, we demonstrate a near-term implementation of extracting the singular vectors with dominant singular values after quantum random projecting a large low-rank matrix to lower dimensions. All such numerical experiments unequivocally demonstrate the ability of local random circuits to randomize a large Hilbert space at sufficiently shorter depths with robust retention of properties of large datasets in reduced dimensions.
In a quantum change point problem, a source emitting particles in a fixed quantum state (default) switches to a different state at some stage, and the objective is to identify when the change happened by measuring a sequence of particles emitted from such a source. Motivated by entanglement-sharing protocols in quantum information, we study this problem within the paradigm of LOCC, short of local operations and classical communication. Here, we consider a source that emits entangled pairs in a default state but starts producing another entangled state (mutation) at a later stage. Then, a sequence of entangled pairs prepared from such a source and shared between distant observers cannot be used for quantum information processing tasks as the identity of each entangled pair remains unknown. We show that identifying the change point using LOCC leads to the distillation of free entangled pairs. In particular, if the default and the mutation are mutually orthogonal, there exists an efficient LOCC protocol that identifies the change point without fail and distills a sufficiently large number of pairs. However, if they are nonorthogonal, there is a probability of failure. In this case, we compute the number of entangled pairs that may be obtained on average. We also consider a relaxation of the two-state problem where the mutation is not known a priori but instead belongs to a known set. Here we show that local distinguishability plays a crucial role: if the default and the possible mutations are locally distinguishable, the problem reduces to the two-state problem with orthogonal states, but if not, one may still identify the mutation, the change point, and distill entanglement, as we illustrate with a concrete example.
In analyses of target detection with Gaussian state transmitters in a thermal background, the thermal occupation is taken to depend on the target reflectivity in a way which simplifies the analysis of the symmetric quantum hypothesis testing problem. However, this assumption precludes comparison of target detection performance between an arbitrary transmitter and a vacuum state transmitter, i.e., ``detection without illumination'', which is relevant in a bright thermal background because a target can be detected by its optical shadow or some other perturbation of the background. Using a target-agnostic thermal environment leads to the result that the oft-claimed 6 dB possible reduction in the quantum Chernoff exponent for a two-mode squeezed vacuum transmitter over a coherent state transmitter in high-occupation thermal background is an unachievable limiting value, only occurring in a limit in which the target detection problem is ill-posed. Further analyzing quantum illumination in a target-agnostic thermal environment shows that a weak single-mode squeezed transmitter performs worse than ``no illumination'', which is explained by the noise-increasing property of reflected low-intensity squeezed light.
In this paper, the Quantum Approximate Optimization Algorithm (QAOA) is analyzed by leveraging symmetries inherent in problem Hamiltonians. We focus on the generalized formulation of optimization problems defined on the sets of $n$-element $d$-ary strings. Our main contribution encompasses dimension reductions for the originally proposed QAOA. These reductions retain the same problem Hamiltonian as the original QAOA but differ in terms of their mixer Hamiltonian, and initial state. The vast QAOA space has a daunting dimension of exponential scaling in $n$, where certain reduced QAOA spaces exhibit dimensions governed by polynomial functions. This phenomenon is illustrated in this paper, by providing partitions corresponding to polynomial dimensions of the corresponding subspaces. As a result, each reduced QAOA partition encapsulates unique classical solutions absent in others, allowing us to establish a lower bound on the number of solutions to the initial optimization problem. Our novel approach opens promising practical advantages in accelerating the algorithm. Restricting the algorithm to Hilbert spaces of smaller dimension may lead to significant acceleration of both quantum and classical simulation of circuits and serve as a tool to cope with barren plateaus problem.
High-harmonic generation has emerged as a pivotal process in strong-field physics, yielding extreme ultraviolet radiation and attosecond pulses with a wide range of applications. Furthermore, its emergent connection with the field of quantum optics has revealed its potential for generating non-classical states of light. Here, we investigate the process of high-harmonic generation in semiconductors under a quantum optical perspective while using a Bloch-based solid-state description. Through the implementation of quantum operations based on the measurement of high-order harmonics, we demonstrate the generation of non-classical light states similar to those found when driving atomic systems. These states are characterized using diverse quantum optical observables and quantum information measures, showing the influence of electron dynamics on their properties. Additionally, we analyze the dependence of their features on solid characteristics such as the dephasing time and crystal orientation, while also assessing their sensitivity to changes in driving field strength. This study provides insights into HHG in semiconductors and its potential for generating non-classical light sources.
In the study of the thermalization of closed quantum systems, the role of kinetic constraints on the temporal dynamics and the eventual thermalization is attracting significant interest. Kinetic constraints typically lead to long-lived metastable states depending on initial conditions. We consider a model of interacting hardcore bosons with an additional kinetic constraint that was originally devised to capture glassy dynamics at high densities. As a main result, we demonstrate that the system is highly prone to localization in the presence of uncorrelated disorder. Adding disorder quickly triggers long-lived dynamics as evidenced in the time evolution of density autocorrelations. Moreover, the kinetic constraint favors localization also in the eigenstates, where a finite-size transition to a many-body localized phase occurs for much lower disorder strengths than for the same model without a kinetic constraint. Our work sheds light on the intricate interplay of kinetic constraints and localization and may provide additional control over many-body localized phases in the time domain.
The generation and evolution of entanglement in quantum many-body systems is an active area of research that spans multiple fields, from quantum information science to the simulation of quantum many-body systems encountered in condensed matter, subatomic physics, and quantum chemistry. Motivated by recent experiments exploring quantum information processing systems with electrons trapped above the surface of cryogenic noble gas substrates, we theoretically investigate the generation of \emph{motional} entanglement between two electrons via their unscreened Coulomb interaction. The model system consists of two electrons confined in separate electrostatic traps which establish microwave frequency quantized states of their motion. We compute the motional energy spectra of the electrons, as well as their entanglement, by diagonalizing the model Hamiltonian with respect to a single-particle Hartree product basis. This computational procedure can in turn be employed for device design and guidance of experimental implementations. In particular, the theoretical tools developed here can be used for fine tuning and optimization of control parameters in future experiments with electrons trapped above the surface of superfluid helium or solid neon.
Entanglement asymmetry is a quantity recently introduced to measure how much a symmetry is broken in a part of an extended quantum system. It has been employed to analyze the non-equilibrium dynamics of a broken symmetry after a global quantum quench with a Hamiltonian that preserves it. In this work, we carry out a comprehensive analysis of the entanglement asymmetry at equilibrium taking the ground state of the XY spin chain, which breaks the $U(1)$ particle number symmetry, and provide a physical interpretation of it in terms of superconducting Cooper pairs. We also consider quenches from this ground state to the XX spin chain, which preserves the broken $U(1)$ symmetry. In this case, the entanglement asymmetry reveals that the more the symmetry is initially broken, the faster it may be restored in a subsystem, a surprising and counter-intuitive phenomenon that is a type of a quantum Mpemba effect. We obtain a quasi-particle picture for the entanglement asymmetry in terms of Cooper pairs, from which we derive the microscopic conditions to observe the quantum Mpemba effect in this system, giving further support to the criteria recently proposed for arbitrary integrable quantum systems. In addition, we find that the power law governing symmetry restoration depends discontinuously on whether the initial state is critical or not, leading to new forms of strong and weak Mpemba effects.
We present several improvements to the recently developed ground state preparation algorithm based on the Quantum Eigenvalue Transformation for Unitary Matrices (QETU), apply this algorithm to a lattice formulation of U(1) gauge theory in 2+1D, as well as propose a novel application of QETU, a highly efficient preparation of Gaussian distributions. The QETU technique has been originally proposed as an algorithm for nearly-optimal ground state preparation and ground state energy estimation on early fault-tolerant devices. It uses the time-evolution input model, which can potentially overcome the large overall prefactor in the asymptotic gate cost arising in similar algorithms based on the Hamiltonian input model. We present modifications to the original QETU algorithm that significantly reduce the cost for the cases of both exact and Trotterized implementation of the time evolution circuit. We use QETU to prepare the ground state of a U(1) lattice gauge theory in 2 spatial dimensions, explore the dependence of computational resources on the desired precision and system parameters, and discuss the applicability of our results to general lattice gauge theories. We also demonstrate how the QETU technique can be utilized for preparing Gaussian distributions and wave packets in a way which outperforms existing algorithms for as little as $n_q \gtrsim 2-5$ qubits.
The quantum digital signature protocol offers a replacement for most aspects of public-key digital signatures ubiquitous in today's digital world. A major advantage of a quantum-digital-signatures protocol is that it can have information-theoretic security, whereas public-key cryptography cannot. Here we demonstrate and characterize hardware to implement entanglement-based quantum digital signatures over our campus network. Over 25 hours, we collect measurements on our campus network, where we measure sufficiently low quantum bit error rates (<5% in most cases) which in principle enable quantum digital signatures at over 50 km as shown through rigorous simulation accompanied by a noise model developed specifically for our implementation. These results show quantum digital signatures can be successfully employed over deployed fiber. Moreover, our reported method provides great flexibility in the number of users, but with reduced entanglement rate per user. Finally, while the current implementation of our entanglement-based approach has a low signature rate, feasible upgrades would significantly increase the signature rate.
A quantum memory is a crucial keystone for enabling large-scale quantum networks. Applicable to the practical implementation, specific properties, i.e., long storage time, selective efficient coupling with other systems, and a high memory efficiency are desirable. Though many quantum memory systems are developed thus far, none of them can perfectly meet all requirements. This work herein proposes a quantum memory based on color centers in hexagonal boron nitride (hBN), where its performance is evaluated based on a simple theoretical model of suitable defects in a cavity. Employing density functional theory calculations, 257 triplet and 211 singlet spin electronic transitions are investigated. Among these defects, it is found that some defects inherit the $\Lambda$ electronic structures desirable for a Raman-type quantum memory and optical transitions can couple with other quantum systems. Further, the required quality factor and bandwidth are examined for each defect to achieve a 95% writing efficiency. Both parameters are influenced by the radiative transition rate in the defect state. In addition, inheriting triplet-singlet spin multiplicity indicates the possibility of being a quantum sensing, in particular, optically detected magnetic resonance. This work therefore demonstrates the potential usage of hBN defects as a quantum memory in future quantum networks.
It has been experimentally demonstrated that molecular-vibration polaritons formed by strong coupling of a molecular vibration to an infrared cavity mode can significantly modify the physical properties and chemical reactivity of various molecular systems. However, a complete theoretical understanding of the underlying mechanisms of the modifications remains elusive due to the complexity of the hybrid system, especially the collective nature of polaritonic states in systems containing many molecules. We develop here the semiclassical theory of molecular-vibration-polariton dynamics based on the truncated Wigner approximation (TWA) that is tractable in large molecular systems and simultaneously captures the quantum character of photons in the optical cavity. The theory is then applied to investigate the nuclear quantum dynamics of a system of identical diatomic molecules having the ground-state Morse potential and strongly coupled to an infrared cavity mode in the ultrastrong coupling regime. The validity of TWA is examined by comparing it with the fully quantum dynamics of a single-molecule system for two different initial states in the dipole and Coulomb gauges. For the initial tensor-product ground state in the dipole gauge, which corresponds to a light-matter entangled state in the Coulomb gauge, the collective and resonance effects of molecular-vibration-polariton formation on the nuclear dynamics are observed in a system of many molecules.
The classical shadows protocol is an efficient strategy for estimating properties of an unknown state $\rho$ using a small number of state copies and measurements. In its original form, it involves twirling the state with unitaries from some ensemble and measuring the twirled state in a fixed basis. It was recently shown that for computing local properties, optimal sample complexity (copies of the state required) is remarkably achieved for unitaries drawn from shallow depth circuits composed of local entangling gates, as opposed to purely local (zero depth) or global twirling (infinite depth) ensembles. Here we consider the sample complexity as a function of the depth of the circuit, in the presence of noise. We find that this noise has important implications for determining the optimal twirling ensemble. Under fairly general conditions, we i) show that any single-site noise can be accounted for using a depolarizing noise channel with an appropriate damping parameter $f$; ii) compute thresholds $f_{\text{th}}$ at which optimal twirling reduces to local twirling for arbitrary operators and iii) $n^{\text{th}}$ order Renyi entropies ($n \ge 2$); and iv) provide a meaningful upper bound $t_{\text{max}}$ on the optimal circuit depth for any finite noise strength $f$, which applies to all operators and entanglement entropy measurements. These thresholds strongly constrain the search for optimal strategies to implement shadow tomography and can be easily tailored to the experimental system at hand.
The Quantum Approximate Optimization Algorithm (QAOA) exhibits significant potential for tackling combinatorial optimization problems. Despite its promise for near-term quantum devices, a major challenge in applying QAOA lies in the cost of circuit runs associated with parameter optimization. Existing methods for parameter setting generally incur at least a superlinear cost concerning the depth p of QAOA. In this study, we propose a novel adiabatic-passage-based parameter setting method that remarkably reduces the optimization cost, specifically when applied to the 3-SAT problem, to a sublinear level. Beginning with an analysis of the random model of the specific problem, this method applies a problem-dependent preprocessing on the problem Hamiltonian analytically, effectively segregating the magnitude of parameters from the scale of the problem. Consequently, a problem-independent initialization is achieved without incurring any optimization cost or pre-computation. Furthermore, the parameter space is adjusted based on the continuity of the optimal adiabatic passage, resulting in a reduction in the disparity of parameters between adjacent layers of QAOA. By leveraging this continuity, the cost to find quasi-optimal parameters is significantly reduced to a sublinear level.
We present a quantum thermometry method utilizing an optomechanical system composed of an optical field coupled to a mechanical resonator for measuring the unknown temperature of a thermal bath. To achieve this, we connect a thermal bath to the mechanical resonator and perform measurements on the optical field, serving as a probe thermometer. Using the open quantum systems approach, we numerically calculate the quantum Fisher information for the probe. We find that, in specific parameter regimes, the system exhibits clusters of densely packed energy eigenstates interspaced with substantial energy gaps. This clustering of energy levels results in quasi-degeneracy within these energy eigenstate groups and hence widens the operational range of temperature estimation. Moreover, thermal sensitivity, especially at low temperatures, can be further boosted by appropriately tuning the essential system parameters.
Two-dimensional electronic spectroscopy (2DES) can be implemented with different geometries, e.g., BOXCARS, collinear and pump-probe geometries. The pump-probe geometry has its advantage of overlapping only two beams and reducing phase cycling steps. However, its applications are typically limited to observe the dynamics with single-quantum coherence and population, leaving the challenge to measure the dynamics of the double-quantum (2Q) coherence, which reflects the many-body interactions. We propose an experimental technique in 2DES under pump-probe geometry with a designed pulse sequence and the signal processing method to extract 2Q coherence. In the designed pulse sequence with the probe pulse arriving earlier than pump pulses, our measured signal includes the 2Q signal as well as the zero-quantum (0Q) signal. With phase cycling and the data processing using causality enforcement, we extract the 2Q signal. The proposal is demonstrated with the rubidium atoms. And we observe the collective resonances of two-body dipole-dipole interactions of both $D_{1}$ and $D_{2}$ lines.
Quantum discord is a form of correlation that is defined as the difference between quantum and classical mutual information of two parties. Due to the optimization involved in the definition of classical mutual information of quantum systems, calculating and distinguishing between discordant and non-discordant states is not a trivial task. Additionally, complete tomography of a quantum state is the prerequisite for the calculation of its quantum discord, and it is indeed resource consuming. Here, by using the relation between the kernels of the convolutional layers of an artificial neural network and the expectation value of operators in quantum mechanical measurements, we design a Convolutional Neural Network (CNN) that uses 16 kernels to completely distinguish between the discordant and non-discordant general two-qubit states. We have also designed a Branching Convolutional Neural Network (BCNN) that can effectively detect quantum discord. Our BCNN achieves an accuracy of around 85% or 99%, by utilizing only 5 or 8 kernels, respectively. Our results show that to detect the existence of quantum discord up to the desired accuracy, instead of complete tomography, one can use suitable quantum circuits to directly measure the expectation values of the kernels, and then a fully connected network will solve the detection problem.
Level statistics is a crucial tool in the exploration of localization physics. The level spacing distribution of the disordered localized phase follows Poisson statistics, and many studies naturally apply it to the quasiperiodic localized phase. However, this is inconsistent with recent mathematical proof results. Here we analytically obtain the level spacing distribution of the quasiperiodic localized phase, which deviates from Poisson statistics. Moreover, based on this level statistics, we derive the ratio of adjacent gaps and find that for a single sample, it is a $\delta$ function, which is in excellent agreement with numerical studies. Additionally, unlike disordered systems, in quasiperiodic systems, there are variations in the level spacing distribution across different regions of the spectrum, and increasing the size and increasing the sample are non-equivalent. Our findings carry significant implications for the reevaluation of level statistics in quasiperiodic systems and a profound understanding of the distinct effects of quasiperiodic potentials and disorder induced localization.
As per the Franck-Condon principle, absorption spectroscopy reveals changes in nuclear geometry in molecules or solids upon electronic excitation. It is often assumed these changes cannot be resolved beyond the ground vibrational wavefunction width ($\sqrt{\hbar/m\omega}$). Here, we show this resolution dramatically improves with highly-excited vibrational initial states (with occupation number $\langle n\rangle$). These states magnify changes in geometry by $2\langle n\rangle +1$, a possibly counterintuitive result given the spatial uncertainty of Fock states grows with $n$. We also discuss generalizations of this result to multimode systems. Our result is relevant to optical spectroscopy, polariton condensates, and quantum simulators ($\textit{e.g.}$, boson samplers).