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Showing votes from 2024-01-09 11:30 to 2024-01-12 12:30 | Next meeting is Tuesday Oct 29th, 10:30 am.
We investigate Lyman-alpha (Ly$\alpha$) transmission spikes at $5.2 < z < 6.8$ using synthetic quasar spectra from the ``Cosmic Reionization On Computers" simulations. We focus on understanding the relationship between these spikes and the properties of the intergalactic medium (IGM). Disentangling the complex interplay between IGM physics and the influence of galaxies on the generation of these spikes presents a significant challenge. To address this, we employ Explainable Boosting Machines, an interpretable machine learning algorithm, to quantify the relative impact of various IGM properties on the Ly$\alpha$ flux. Our findings reveal that gas density is the primary factor influencing absorption strength, followed by the intensity of background radiation and the temperature of the IGM. Ionizing radiation from local sources (i.e. galaxies) appears to have a minimal effect on Ly$\alpha$ flux. The simulations show that transmission spikes predominantly occur in regions of low gas density. Our results challenge recent observational studies suggesting the origin of these spikes in regions with enhanced radiation. We demonstrate that Ly$\alpha$ transmission spikes are largely a product of the large-scale structure, of which galaxies are biased tracers.
We present a novel approach to measuring the expansion rate and the geometry of the Universe, which combine time-delay cosmography in lens galaxy clusters with pure samples of 'cosmic chronometers' (CCs) by probing the member galaxies. The former makes use of the measured time delays between the multiple images of time-varying sources strongly lensed by galaxy clusters, while the latter exploits the most massive and passive cluster member galaxies to measure the differential time evolution of the Universe. We applied two different statistical techniques, adopting realistic errors on the measured quantities, to assess the accuracy and the gain in precision on the values of the cosmological parameters. We demonstrate that the proposed combined method allows for a robust and accurate measurement of the value of the Hubble constant. In addition, this provides valuable information on the other cosmological parameters thanks to the complementarity between the two different probes in breaking parameter degeneracies. Finally, we showcase the immediate observational feasibility of the proposed joint method by taking advantage of the existing high-quality spectro-photometric data for several lens galaxy clusters.
We present high-definition observations with the James Webb Space Telescope of >1000 Cepheids in a geometric anchor of the distance ladder, NGC4258, and in 5 hosts of 8 SNe~Ia, a far greater sample than previous studies with JWST. These galaxies individually contain the largest samples of Cepheids, an average of >150 each, producing the strongest statistical comparison to those previously measured with the Hubble Space Telescope in the NIR. They also span the distance range of those used to determine the Hubble constant with HST, allowing us to search for a distance-dependent bias in HST measurements. The superior resolution of JWST negates crowding noise, the largest source of variance in the NIR Cepheid Period-Luminosity relations (Leavitt laws) measured with HST. Together with the use of two-epochs to constrain Cepheid phases and three filters to remove reddening, we reduce the dispersion in the Cepheid PL relations by a factor of 2.5. We find no significant difference in the mean distance measurements determined from HST and JWST, with a formal difference of -0.01+/-0.03 mag. This result is independent of zeropoints and analysis variants including metallicity dependence, local crowding, choice of filters, and relation slope. We can reject the hypothesis of unrecognized crowding of Cepheid photometry from HST that grows with distance as the cause of the ``Hubble Tension'' at 8.2 sigma, i.e., greater confidence than that of the Hubble Tension itself. We conclude that errors in photometric measurements of Cepheids across the distance ladder do not significantly contribute to the Tension.
The tip of the red giant branch (TRGB) allows for the measurement of precise and accurate distances to nearby galaxies, based on the brightest ascent of low-mass red giant branch stars before they undergo the helium flash. With the advent of JWST, there is great promise to utilize the technique to measure galaxy distances out to at least 50 Mpc, significantly further than HST's reach of 20 Mpc. However, with any standard candle, it is first necessary to provide an absolute reference. Here we use Cycle 1 data to provide an absolute calibration in the F090W filter. F090W is most similar to the F814W filter commonly used for TRGB measurements with HST, which had been adopted by the community due to minimal dependence from the underlying metallicities and ages of stars. The imaging we use was taken in the outskirts of NGC 4258, which has a direct geometrical distance measurement from the Keplerian motion of its water megamaser. Utilizing several measurement techniques, we find $M_{TRGB}^{F090W}$ = -4.362 $\pm$ 0.033 (stat) $\pm$ 0.045 (sys) mag (Vega) for the metal-poor TRGB. We also perform measurements of the TRGB in two Type Ia supernova hosts, NGC 1559, and NGC 5584. We find good agreement between our TRGB distances and previous distance determinations to these galaxies from Cepheids ($\Delta$ = 0.01 $\pm$ 0.06 mag), with these differences being too small to explain the Hubble tension ($\sim$0.17 mag). As a final bonus, we showcase the serendipitous discovery of a faint dwarf galaxy near NGC 5584.
We study stars in the J-regions of the asymptotic giant branch (JAGB) of near-infrared color magnitude diagrams in the maser host NGC 4258 and 4 hosts of 6 Type Ia supernovae (SN~Ia): NGC 1448, NGC 1559, NGC 5584, and NGC 5643. These clumps of stars are readily apparent near $1.0< F150W-F277W <1.5$ and $m_{F150W}$=22-25 mag with \textit{James Webb Space Telescope} NIRCam photometry. Various methods have been proposed to assign an apparent reference magnitude for this recently proposed standard candle, including the mode, median, sigma-clipped mean or a modeled parameter of its luminosity function. We test the consistency of these by measuring intra-host variations, finding differences of up to $\sim$0.2 mag that significantly exceed statistical uncertainties. Brightness differences appear intrinsic, and are further amplified by the non-uniform shape of the JAGB LF, an issue already apparent in comparing the LMC and SMC. We follow a ``many methods'' approach to consistently measure JAGB magnitudes and distances to the SN Ia host sample calibrated by NGC 4258. We find broad agreement with the distances measured from Cepheids, tip of the red giant branch (TRGB) and Miras. However, the SN host mean distance estimated via the JAGB method and necessary to estimate $H_0$, differs by $\sim$ 0.18 mag amongst the above definitions, a result of the different levels of asymmetry of the JAGB luminosity functions. The methods yield a full range of $72-78$ km s$^{-1}$ Mpc$^{-1}$, i.e., a fiducial result of $H_0=74.7 \pm 2.2$ (stat) $\pm$ 2.3 (sys) ($\pm$ 3.2 if combined in quadrature) km s$^{-1}$ Mpc$^{-1}$, independent of Cepheids, TRGB, or Miras, with systematic errors limited by the differences in methods. Future work may seek to further standardize and refine this promising tool, making it more competitive with established distance indicators.
Modified Newtonian Dynamics (MOND), postulating a breakdown of Newtonian mechanics at low accelerations, has considerable success at explaining galaxy kinematics. However, the quadrupole of the gravitational field of the Solar System (SS) provides a strong constraint on the way in which Newtonian gravity can be modified. In this paper we assess the extent to which modified gravity formulations of MOND are capable of accounting simultaneously for the Radial Acceleration Relation (RAR) -- encapsulating late-type galaxy dynamics -- the Cassini measurement of the SS quadrupole and the kinematics of wide binaries in the Solar neighbourhood. We achieve this by extending the method of Desmond (2023) to infer the location and sharpness of the MOND transition from the SPARC RAR under broad assumptions for the behaviour of the interpolating function and external field effect. We constrain the same quantities from the SS quadrupole, finding that it requires a significantly sharper transition between the deep-MOND and Newtonian regimes than is allowed by the RAR (an 8.7$\sigma$ tension under fiducial model assumptions). This may be relieved by allowing additional freedom in galaxies' mass-to-light ratios -- which also provides a better RAR fit -- and more significantly by removing galaxies with bulges. We show that the SS quadrupole constraint implies, to high precision, no deviation from Newtonian gravity in wide binaries in the Solar neighbourhood, and speculate on possible resolutions of this incompatibility between SS and galaxy data within the MOND paradigm.
In our galaxy, the white dwarfs (WDs) will inevitably capture the dark matter (DM) particles streaming through them, if there exist interactions between DM particles and nucleons/electrons. At the same time, these DM particles can also be evaporated by the nucleons/electrons in a WD if they have proper mass. The evaporation of DM particles will lead to a faster cooling evolution than that predicted by stellar evolution theory. In this letter, we ascribe the faster cooling evolution of 3 observed WDs to the capture and evaporation of DM particles, and get possible DM signals as follows: for $F(q) = 1$, $40\ \mathrm{MeV}/c^{2} \lesssim m_{\chi} \lesssim 70\ \mathrm{MeV}/c^{2}$ and $10^{-57} \mathrm{cm}^{2} \lesssim \sigma_{\chi,e} \lesssim 10^{-55} \mathrm{cm}^{2}$; for $F(q) = (\alpha m_{e})^{2}/q^{2}$, $30\ \mathrm{MeV}/c^{2} \lesssim m_{\chi} \lesssim 60\ \mathrm{MeV}/c^{2}$ and $10^{-53} \mathrm{cm}^{2} \lesssim \sigma_{\chi,e} \lesssim 10^{-51} \mathrm{cm}^{2}$. These results should be cross checked by more novel scenarios in the future.
Methods are studied to compute the boosting effects produced by the observer motion that modifies and transfers to higher l the isotropic monopole frequency spectrum of the cosmic background. Explicit analytical solutions for spherical harmonic coefficients are presented and applied to various background spectra, alleviating computational effort. High l frequency spectra are led by higher order derivatives of the spectrum. Tabulated frequency spectra are computed with a relatively poor frequency resolution in comparison with the Doppler shift, calling for interpolation. They are affected by uncertainties due to intrinsic inaccuracies in modelling, observational data or limited computation accuracy, propagate and increase with the derivative order, possibly preventing a trustworthy computation to higher l and of the observed monopole. We filter the original function and the multipole spectra to derive reliable predictions of the harmonic coefficients. For spectra expressed in Taylor series, we derive explicit solutions for the harmonic coefficients up to l=6 in terms of spectra derivatives. We consider filters and study the quality of these methods on suitable analytical approximations, polluted with simulated noise. We consider the extragalactic sources microwave background from radio loud AGN and the 21cm line superimposed to the CMB. Gaussian pre-filtering coupled to a real space filtering of derivatives allows accurate predictions up to l=6, while log-log polynomial representation gives accurate solutions at any l. Describing the 21 cm model variety is difficult, so it is relevant to relax assumptions. Pre-filtering gives accurate predictions up to l=3-4, while further filtering or boosting amplification/deamplification method improves the results allowing reasonable estimations. The methods can extend the range of realistic background models manageable with a fast computation.
Flavor-dependent neutrino transport is described by a well-known kinetic equation for occupation-number matrices in flavor space. However, as an overlooked theoretical problem, we show that in the inhomogeneous case, neutrino-neutrino refractive energy is not conserved. We derive the missing gradient terms in the fast flavor limit (vanishing neutrino masses), and prove that the missing refractive energy is traded with the huge reservoir of neutrino kinetic energy through gradients of the weak interaction potential. Even small changes of the kinetic energy accommodate the refractive energy gained or lost. Flavor evolution alone is negligibly affected by the new terms.
We obtain bounds on dark matter annihilation using 14 years of publicly available Fermi-LAT data from a set of 54 dwarf spheroidal galaxies, using spectral information from 16 energy bins. We perform this analysis using our updated and publicly available code MADHATv2, which can be used to test a variety of models for dark matter particle physics and astrophysics in an accessible manner. In particular, we note that including Carina III in the analysis strengthens constraints on $s$-wave annihilation into two-body Standard Model final states by a factor of $\sim 3$ but broadens the error on the constraint due to the large uncertainty of its $J$-factor. Our findings illustrate the importance of verifying if Carina III is in fact a dwarf spheroidal galaxy and measuring more precisely its $J$-factor. More generally, they highlight the significance of forthcoming discoveries of nearby ultra-faint dwarfs for dark matter indirect detection.
The cosmic 21-cm line of hydrogen is expected to be measured in detail by the next generation of radio telescopes. The enormous dataset from future 21-cm surveys will revolutionize our understanding of early cosmic times. We present a machine learning approach based on an Artificial Neural Network that uses emulation in order to uncover the astrophysics in the epoch of reionization and cosmic dawn. Using a seven-parameter astrophysical model that covers a very wide range of possible 21-cm signals, over the redshift range 6 to 30 and wavenumber range $0.05$ to $1 \ \rm{Mpc}^{-1}$ we emulate the 21-cm power spectrum with a typical accuracy of $10 - 20\%$. As a realistic example, we train an emulator using the power spectrum with an optimistic noise model of the Square Kilometre Array (SKA). Fitting to mock SKA data results in a typical measurement accuracy of $2.8\%$ in the optical depth to the cosmic microwave background, $34\%$ in the star-formation efficiency of galactic halos, and a factor of 9.6 in the X-ray efficiency of galactic halos. Also, with our modeling we reconstruct the true 21-cm power spectrum from the mock SKA data with a typical accuracy of $15 - 30\%$. In addition to standard astrophysical models, we consider two exotic possibilities of strong excess radio backgrounds at high redshifts. We use a neural network to identify the type of radio background present in the 21-cm power spectrum, with an accuracy of $87\%$ for mock SKA data.
We formulate the Effective Field Theory (EFT) of perturbations within scalar-tensor theories on an inhomogeneous background. The EFT is constructed while keeping a background of a scalar field to be $\textit{timelike}$, which spontaneously breaks the time diffeomorphism. We find a set of consistency relations that are imposed by the invariance of the EFT under the 3d spatial diffeomorphism. This EFT can be generically applied to any inhomogeneous background metric as long as the scalar profile is everywhere timelike. For completeness, we report a dictionary between our EFT parameters to those of Horndeski theories. Finally, we compute background equations for a class of spherically symmetric, static black hole backgrounds, including a stealth Schwarzschild-de Sitter solution.
Next-generation spectroscopic surveys such as the MegaMapper, MUltiplexed Survey Telescope (MUST), MaunaKea Spectroscopic Explorer (MSE), and Wide Spectroscopic Telescope (WST) are foreseen to increase the number of galaxy/quasar redshifts by an order of magnitude, with hundred millions of spectra that will be measured at $z>2$. We perform a Fisher matrix analysis for these surveys on the baryonic acoustic oscillation (BAO), the redshift-space distortion (RSD) measurement, the non-Gaussianity amplitude $f_{\rm NL}$, and the total neutrino mass $M_\nu$. For BAO and RSD parameters, these surveys may achieve precision at sub-percent level (<0.5 per cent), representing an improvement of factor 10 w.r.t. the latest database. For NG, these surveys may reach an accuracy of $\sigma(f_{\rm NL})\sim 1$. They can also put a tight constraint on $M_\nu$ with $\sigma(M_\nu) \sim 0.02\,\rm eV$ if we do joint analysis with Planck and even $ 0.01\,\rm eV$ if combined with other data. In addition, we introduce a general survey model, to derive the cosmic volume and number density of tracers, given instrumental facilities and survey strategy. Using our Fisher formalism, we can explore (continuously) a wide range of survey observational parameters, and propose different survey strategies that optimise the cosmological constraints. Fixing the fibre number and survey duration, we show that the best strategy for $f_{\rm NL}$ and $M_\nu$ measurement is to observe large volumes, despite the noise increase. However, the strategy differs for the apparent magnitude limit. Finally, we prove that increasing the fibre number improves $M_{\nu}$ measurement but not significantly $f_{\rm NL}$.
We discuss a novel window to probe the origin of our universe via the mass functions of primordial black holes (PBHs). The mass functions of PBHs are simply estimated using the conventional Press-Schechter formalism for two paradigms of cosmic origin, including inflationary $\Lambda$CDM and bounce cosmology. The standard inflationary $\Lambda$CDM model cannot generate an appreciable number of massive PBHs; however, non-trivial inflation models with blue-tilted power spectra at small scales and matter bounce cosmology provide formation mechanisms for heavy PBHs, which in turn, may seed the observed supermassive black holes (SMBHs). By fitting the SMBH mass functions at high redshift ($z \sim 6$) derived from Sloan Digital Sky Survey (SDSS) and Canada-France High-z Quasar Survey (CFHQS) quasars, for two paradigms of cosmic origin, we derive constraints on the PBH density fraction $f_{\mathrm{PBH}}$ at $z \sim 6$ and the characteristic mass $M_{\star}$, with the prior assumption that all SMBHs stem from PBHs. We demonstrate that this newly proposed procedure, relying on astronomical measurements that utilize deep-field surveys of SMBHs at high redshift, can be used to constrain models of cosmic origin. Additionally, although not the main focus of this paper, we evolve the mass function from $z\sim6$ to $z\sim0$ through an assumption of $3\times 10^8$-year Eddington's accretion, and give a rough estimation of $f_{\mathrm{PBH}}$ at $z \sim 0$.
We analyze inhomogeneous cosmological models in the local Universe, described by the Lema\^itre-Tolman-Bondi (LTB) metric and developed using linear perturbation theory on a homogeneous and isotropic Universe background. Focusing on the different evolution of spherical symmetric inhomogeneities, we compare the $\Lambda$LTB model, in which the cosmological constant $\Lambda$ is included in the LTB formalism, with inhomogeneous cosmological models based on $f\left(R\right)$ modified gravity theories viewed in the Jordan frame. We solve the system of field equations for both inhomogeneous cosmological models adopting the method of separation of variables: we integrate analytically the radial profiles of local perturbations, while their time evolution requires a numerical approach. The main result of the analysis concerns the different radial profiles of local inhomogeneities due to the presence of a non-minimally coupled scalar field in the Jordan frame of $f\left(R\right)$ gravity. While radial perturbations follow a power-law in the $\Lambda$LTB model, Yukawa-like contributions appear in the $f\left(R\right)$ theory. Interestingly, this latter peculiar behavior of radial profile is not affected by the choice of the $f\left(R\right)$ functional form. The numerical solution of time-dependent perturbations exhibits a non-diverging profile. This work suggests that investigations about local inhomogeneities in the late Universe may allow us to discriminate if the present cosmic acceleration is caused by a cosmological constant term or a modified gravity effect.
We discuss the discovery potential of the Dark-photons & Axion-Like particles Interferometer (DALI) in this letter. The apparatus, currently in a design and prototyping phase, will probe axion dark matter from the Teide Observatory, an environment protected from terrestrial microwave sources, reaching Dine-Fischler-Srednicki-Zhitnitsky-like axion sensitivity in the range 25-250 $\mu$eV of mass. The experimental approach shows also a potential to probe dark sector photons of kinetic mixing strength in excess of several $10^{-16}$; and to establish new constraints to a stochastic gravitational wave background in its band. We identify different branches, including cosmology, stellar and particle physics, where this next-generation halo-telescope may play a role in coming years.
Warm Dark Matter (WDM) particles with masses ($\sim$ kilo electronvolt) offer an attractive solution to the small-scale issues faced by the Cold Dark Matter (CDM) paradigm. The delay of structure formation in WDM models and the associated dearth of low-mass systems at high-redshifts makes this an ideal time to revisit WDM constraints in light of the unprecedented data-sets from the James Webb Space Telescope (JWST). Developing a phenomenological model based on the halo mass functions in CDM and WDM models, we calculate high-redshift ($z \gt 6$) the stellar mass functions (SMF) and the associated stellar mass density (SMD) and the maximum stellar mass allowed in a given volume. We find that: (i) WDM as light as 1.5 keV is already disfavoured by the low-mass end of the SMF (stellar mass $M_* \sim 10^7 \rm{M_\odot}$) although caution must be exerted given the impact of lensing uncertainties; (ii) 1.5 keV WDM models predict SMD values that show a steep decrease from $10^{8.8}$ to $10^{2} ~{\rm M_\odot ~cMpc^{-3}}$ from $z \sim 4$ to 17 for $M_* \gt 10^8 \rm{M_\odot}$; (iii) the 1.5 keV WDM model predicts a sharp and earlier cut-off in the maximum stellar masses for a given number density (or volume) as compared to CDM or heavier WDM models. For example, with a number density of $10^{-3} \rm {cMpc^{-3}}$, 1.5 (3) KeV WDM models do not predict bound objects at $z \gt 12$ (18). Forthcoming JWST observations of multiple blank fields can therefore be used as a strong probe of WDM at an epoch inaccessible by other means.
Evidence Networks can enable Bayesian model comparison when state-of-the-art methods (e.g. nested sampling) fail and even when likelihoods or priors are intractable or unknown. Bayesian model comparison, i.e. the computation of Bayes factors or evidence ratios, can be cast as an optimization problem. Though the Bayesian interpretation of optimal classification is well-known, here we change perspective and present classes of loss functions that result in fast, amortized neural estimators that directly estimate convenient functions of the Bayes factor. This mitigates numerical inaccuracies associated with estimating individual model probabilities. We introduce the leaky parity-odd power (l-POP) transform, leading to the novel ``l-POP-Exponential'' loss function. We explore neural density estimation for data probability in different models, showing it to be less accurate and scalable than Evidence Networks. Multiple real-world and synthetic examples illustrate that Evidence Networks are explicitly independent of dimensionality of the parameter space and scale mildly with the complexity of the posterior probability density function. This simple yet powerful approach has broad implications for model inference tasks. As an application of Evidence Networks to real-world data we compute the Bayes factor for two models with gravitational lensing data of the Dark Energy Survey. We briefly discuss applications of our methods to other, related problems of model comparison and evaluation in implicit inference settings.
We investigate the impact of a galaxy's merger history on its system of satellites using the new \textsc{vintergatan-gm} suite of zoom-in hydrodynamical simulations of Milky Way-mass systems. The suite simulates five realizations of the same halo with targeted `genetic modifications' (GMs) of a $z \approx 2$ merger, but resulting in the same halo mass at $z=0$. We find that differences in the satellite stellar mass functions last for $2.25-4.25$ Gyr after the $z \approx 2$ merger; specifically, the haloes that have undergone smaller mergers host up to 60\% more satellites than those of the larger merger scenarios. However, by $z=0$ these differences in the satellite stellar mass functions have been erased. The differences in satellite numbers seen soon after the mergers are driven by several factors, including the timings of significant mergers (with $M_{\rm 200c}$ mass ratios $>1:30$ and bringing in $M_{\rm *} \geq 10^{8}{\rm M}_{\odot}$ at infall), the masses and satellite populations of the central and merging systems, and the subsequent extended history of smaller mergers. The results persist when measured at fixed central stellar mass rather than fixed time, implying that a host's recent merger history can be a significant source of scatter when reconstructing its dynamical properties from its satellite population.
The interaction of neutrinos with ultralight scalar and vector dark matter backgrounds induce a modification of the neutrino dispersion relation. The effects of this modification are reviewed in the framework of asymmetric emission of neutrinos from the supernova core, and, in turn, of pulsar kicks. We consider the neutrino oscillations, focusing in particular to active-sterile conversion. The ultralight dark matter induced neutrino dispersion relation contains a term of the form $\delta {\bf \Omega}\cdot \hat{{\bf{p}}}$, where $\delta {\bf \Omega}$ is related to the ultralight dark matter field and $\hat{{\bf p}}$ is the unit vector along the direction of neutrino momentum. The relative orientation of ${\bf p}$ with respect to $\delta {\bf \Omega}$ affects the mechanism for the generation of the observed pulsar velocities. We obtain the resonance condition for the active-sterile neutrino oscillation in ultralight dark matter background and calculate the star parameters in the resonance surface so that both ultralight scalar and vector dark matter backgrounds can explain the observed pulsar kicks. The asymmetric emission of neutrinos in presence of ultralight dark matter background results gravitational memory signal which can be probed from the future gravitational wave detectors such as adLIGO (advanced LIGO), adVIRGO (advanced VIRGO), DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), BBO (Big Bang Observer), and ET (Einstein Telescope). We also establish a relation between the ultralight dark matter parameters and the Lorentz and CPT invariance violation parameters.
The relation between giant radio halos and mini-halos in galaxy clusters is not understood. The former are usually associated with merging clusters, the latter are found in relaxed systems. In the last years, the advent of low-frequency radio observations has challenged this dichotomy, finding intermediate objects with a hybrid radio morphology. We aim to investigate the presence of diffuse radio emission in the cluster Abell 1413 and determine its dynamical status. We used LOFAR HBA observations centred at 144 MHz to study the diffuse emission hosted by this cluster.To investigate the dynamical state of the system, we complete our study with newly analysed XMM-Newton archival data. A1413 shows features that are typically present in both relaxed (e.g., peaked x-ray surface brightness distribution and little large-scale inhomogeneities) and disturbed (e.g., flatter temperature and metallicity profiles) clusters.This evidence supports the scenario that A1413 is neither a disturbed nor fully relaxed object. We argue that it is an intermediate-phase cluster.Using radio observations at 144 MHz, we discover the presence of a wider diffuse component surrounding the previously reported mini-halo at the cluster centre. By fitting the radio surface brightness profile with a double-exponential model, we can disentangle the two components. We find an inner mini-halo with an e-folding radius r_e1=28 kpc and the extended component with r_e2 = 290 kpc. We also performed point-to-point correlations between radio and X-ray surface brightness, finding a sub-linear relation for the outer emission and a super-linear relation for the mini-halo.The mini-halo and the diffuse emission extend over different scales and show different features, confirming the double nature of the radio emission and suggesting that the mechanisms responsible for the re-acceleration of the radio-emitting particle might be different.
Bright galaxies at sub-millimetre wavelengths from Herschel are now well known to be predominantly strongly gravitationally lensed. The same models that successfully predicted this strongly lensed population also predict about one percent of faint $450{\mu}$m-selected galaxies from deep James Clerk Maxwell Telescope (JCMT) surveys will also be strongly lensed. Follow-up ALMA campaigns have so far found one potential lens candidate, but without clear compelling evidence e.g. from lensing arcs. Here we report the discovery of a compelling gravitational lens system confirming the lensing population predictions, with a $z_{s} = 3.4 {\pm} 0.4$ submm source lensed by a $z_{spec} = 0.360$ foreground galaxy within the COSMOS field, identified through public JWST imaging of a $450{\mu}$m source in the SCUBA-2 Ultra Deep Imaging EAO Survey (STUDIES) catalogue. These systems will typically be well within the detectable range of future wide-field surveys such as Euclid and Roman, and since sub-millimetre galaxies are predominantly very red at optical/near-infrared wavelengths, they will tend to appear in near-infrared channels only. Extrapolating to the Euclid-Wide survey, we predict tens of thousands of strongly lensed near-infrared galaxies. This will be transformative for the study of dusty star-forming galaxies at cosmic noon, but will be a contaminant population in searches for strongly lensed ultra-high-redshift galaxies in Euclid and Roman.
The no-scale flipped SU(5) superstring framework constitutes a very promising paradigm for physics below the Planck scale providing us with a very rich cosmological phenomenology in accordance with observations. In particular, it can accommodate Starobinsky-like inflation, followed by a reheating phase, which is driven by a light "flaton" field, and during which the GUT phase transition occurs. In this Letter, we extract for the first time a gravitational-wave (GW) signal which naturally arises in the context of the flipped SU(5) cosmological phenomenology and is related to the existence of an early matter era (eMD) driven by the flaton field. Specifically, we study GWs non-linearly induced by inflationary perturbations and which are abundantly produced during a sudden transition from the flaton-driven eMD era to the late-time radiation-dominated era. Remarkably, we find a GW signal with a characteristic peak frequency $f_\mathrm{GW,peak}$ depending only on the string slope $\alpha'$ and reading as $f_\mathrm{GW,peak} \propto 10^{-9} \left(\frac{\alpha'}{\alpha'_*}\right)^4 \mathrm{Hz}$, where $\alpha'_*$ is the fiducial string slope being related directly to the reduced Planck scale $M_\mathrm{Pl}$ as $\alpha'_* = 8/M^2_\mathrm{Pl}$. Interestingly enough, $f_\mathrm{GW,peak}$ lies within the $\mathrm{nHz}$ frequency range; hence rendering this primordial GW signal potentially detectable by SKA, NANOGrav and PTA probes at their very low frequency region of their detection bands.
The recent stochastic signal observed jointly by NANOGrav, PPTA, EPTA, and CPTA can be accounted for by scalar-induced gravitational waves (SIGWs). The source of the SIGWs is from the primordial curvature perturbations, and the main contribution to the SIGWs is from the peak of the primordial curvature power spectrum. To effectively model this peak, we apply the Taylor expansion to parameterize it. With the Taylor expansion parameterization, we apply Bayesian methods to constrain the primordial curvature power spectrum based on the NANOGrav 15-year data set. The constraint on the primordial curvature power spectrum possesses a degree of generality, as the Taylor expansion can effectively approximate a wide range of function profiles.
Excursion set theory is a powerful and widely used tool for describing the distribution of dark matter haloes, but it is normally applied with simplifying approximations. We use numerical sampling methods to study the mass functions predicted by the theory without approximations. With a spherical top-hat window and a constant $\delta=1.5$ threshold, the theory accurately predicts mass functions with the $M_{200}$ mass definition, both unconditional and conditional, in simulations of a range of matter-dominated cosmologies. For $\Lambda$CDM at the present epoch, predictions lie between the $M_\mathrm{200m}$ and $M_\mathrm{200c}$ mass functions. In contrast, with the same window function, a nonconstant threshold based on ellipsoidal collapse predicts uniformly too few haloes. This work indicates a new way to simply and accurately evaluate halo mass functions, clustering bias, and assembly histories for a range of cosmologies. We provide a simple fitting function that accurately represents the predictions of the theory for a wide range of parameters.
We generalize Integration-By-Parts (IBP) and differential equations methods to de Sitter correlators related to inflation. While massive correlators in de Sitter spacetime are usually regarded as highly intricate, we find they have remarkably hidden concise structures from the perspective of IBP. We find the irrelevance of IBP relations to propagator-types. This also leads to the factorization of the IBP relations of each vertex integral family corresponding to $\mathrm{d} \tau_i$ integration. Furthermore, with a smart construction of master integrals, the universal formulas for iterative reduction and $\mathrm{d} \log$-form differential equations of arbitrary vertex integral family are presented and proved. These formulas dominate all tree-level de Sitter correlators and play a kernel role at the loop-level as well.
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.
The construction of high-resolution shock-capturing schemes is vital in producing highly accurate gravitational waveforms from neutron star binaries. The entropy based flux limiting (EFL) scheme is able to perform fast converging binary neutron star merger simulations reaching up to fourth-order convergence in the gravitational waveform phase. Here, we extend the applicability of the EFL method beyond special/general relativistic hydrodynamics to scalar conservation laws and show how to treat systems without a thermodynamic entropy. This is an indication that the method has universal applicability to any system of partial differential equations that can be written in conservation form. We also present some further very challenging special/general relativistic hydrodynamics applications of the EFL method and use it to construct eccentricity reduced initial data for a specific neutron star binary and show up to optimal fifth-order convergence in the gravitational waveform phase for this simulation.
Quasi-periodic oscillations (QPOs) have been widely observed in black hole X-ray binaries (BHBs), which often exhibit significant X-ray variations. Extensive research has explored the long-term evolution of the properties of QPOs in BHBs. In contrast, such evolution in active galactic nuclei (AGNs) has remained largely unexplored due to limited observational data. By using the 10 new XMM-Newton observations for the narrow-line Seyfert 1 galaxy RE J1034+396 from publicly available data, we analyze the characteristics of its X-ray QPOs and examine their long-term evolution. The hard-band (1--4 keV) QPOs are found in all 10 observations and the frequency of these QPOs evolves ranging at $(2.47\text{--}2.83)\times10^{-4}\rm\ Hz$. Furthermore, QPO signals in the soft (0.3--1 keV) and hard bands exhibit strong coherence, although, at times, the variations in the soft band lead those in the hard band (the hard-lag mode), while at other times, it is the reverse (the soft-lag mode). The observations presented here serendipitously captured two ongoing lag reversals within about two weeks, which are first seen in RE J1034+396 and also among all AGNs. A transition in QPO frequency also takes place within a two-week timeframe, two weeks prior to its corresponding lag reversal, indicating a possible coherence between the transitions of QPO frequency and lag mode with delay. The diagram of time lag versus QPO frequency clearly evidences this interconnected evolution with hysteresis, which is, for the first time, observed among AGNs.
The prompt emission, X-ray plateau, and X-ray flares of GRB are thought to be from internal dissipation, and the magnetar as the central engine with propeller-fallback-accretion is proposed to interpret the observed phenomena of GRB. In this paper, by systematically searching for X-ray emission observed by Swift/XRT, we find that seven robust GRBs include both X-ray flares and plateau emissions with measured redshift. More interestingly, the X-ray flare/bump for those seven GRBs are simultaneously observed in $\gamma-$ray band. By adopting the propeller-fallback-accretion model to fit the observed data, it is found that the free parameters of two GRBs (140512A and 180329B) can be constrained very well, while the other five cases, more or less, are not all sufficiently constrained. On the other hand, it requires that the conversion efficiency of propeller is two or three times higher than that of spin-down dipole radiation of magnetar. If this is the case, it is contradictory to the expectation from the propeller model, namely, a dirtier ejecta should be less efficient in producing $\gamma-$ray emissions. Our results hint that at least the magnetar central engine with propeller-fallback-accretion model cannot interpret very well both the GRB X-ray flares simultaneously observed in $\gamma-$ray band and the X-ray flares of GRB with a high Lorentz factor.
Supernova remnants interacting with molecular/atomic clouds are interesting X-ray sources to study broadband nonthermal emission. X-ray line emission in these systems can be produced by different processes, e.g. low energy cosmic rays interacting with the cloud and fast ejecta fragments moving in the cloud. The paper aims at studying the origin of the non-thermal X-ray emission of the southwestern limb of SN 1006 beyond the main shock, in order to distinguish if the emission is due to low energy cosmic rays diffusing in the cloud or to ejecta knots moving into the cloud. We analyzed the X-ray emission of the southwestern limb of SN 1006, where the remnant interacts with an atomic cloud, with three different X-ray telescopes ({NuSTAR, Chandra and XMM-Newton) and performed a combined spectro-imaging analysis of this region. The analysis of the non thermal X-ray emission of the southwestern limb of SN 1006, interacting with an atomic cloud, has shown the detection of an extended X-ray source in the atomic cloud, approximately $2$ pc upstream of the shock front. The source is characterized by a hard continuum (described by a power law with photon index $\Gamma\sim1.4$) and by Ne, Si and Fe emission lines. The observed flux suggests that the origin of the X-ray emission is not associated with low energy cosmic rays interacting with the cloud. On the other hand, the spectral properties of the source, together with the detection of an IR counterpart visible with \textit{Spitzer}-MIPS at 24 $\mu$m are in good agreement with expectations for a fast ejecta fragment moving within the atomic cloud. We detected X-ray and IR emission from a possible ejecta fragment, with radius approximately 1$\times10^{17}$ cm, and mass approximately $10^{-3}M_\odot$ at about 2 pc out of the shell of SN 1006, in the interaction region between the southwestern limb of the remnant and the atomic cloud.
The jet composition of GRB plays an important role in understanding the energy dissipation and radiation mechanisms in GRB physics, but it is poorly constrained from the observational data. Recently, an interesting long-duration GRB 230307A with redshift $z=$0.065 has attracted great attention. The lack of detected thermal emission and mini-structure of prompt emission lightcurve of this burst suggest that the outflow is Poynting-flux-dominated and point towards the ICMART model. In this paper, we invoke two independent methods to investigate the jet composition of GRB 230307A. The high magnetization parameter ($\sigma>7$ or ever large) for$R_0=10^{10}$ cm that is used to suppress thermal component, strongly suggests that a significant fraction of the outflow energy is likely in a Poynting flux entrained with the baryonic matter. Moreover, it is found that the radiation efficiency of this burst for typical values $\epsilon_e=0.1$ and $\epsilon_B=0.01$ can reach as high as $~50\%$ which disfavors the internal shock model, but is consistent with ICMART model. Finally, a possible unified picture to produce GRB 230307A originated from a compact star merger is also discussed.
Electron-capture supernovae (EC-SNe) provide an alternative channel for producing neutron stars (NSs). They play an important role in the formation of double NS (DNS) systems and the chemical evolution of galaxies, and contribute to the NS mass distribution in observations. It is generally believed that EC-SNe originate from $e$-captures on $\rm^{24}Mg$ and $\rm^{20}Ne$ in the massive degenerate oxygen-neon (ONe) cores with masses close to the Chandrasekhar limit ($M_{\rm Ch}$). However, the origin of EC-SNe is still uncertain. In this paper, we systematically studied the EC-SNe in NS+He star systems by considering the explosive oxygen burning that may occur in the near-$M_{\rm Ch}$ ONe core. We provided the initial parameter spaces for producing EC-SNe in the initial orbital period $-$ initial He star mass (log$P_{\rm orb}^{\rm i}-M_{\rm He}^{\rm i}$) diagram, and found that both $M_{\rm He}^{\rm i}$ and minimum $P_{\rm orb}^{\rm i}$ for EC-SNe increase with metallicity. Then, by considering NS kicks added to the newborn NS, we investigated the properties of the formed DNS systems after the He star companions collapse into NSs, such as the orbital periods, eccentricities and spin periods of recycle pulsars ($P_{\rm spin}$), etc. The results show that most of the observed DNS systems can be produced by NS kicks of $\lesssim50\rm\,km\,s^{-1}$. In addition, we found that NSs could accrete more material if the residual H envelope on the He star companions is considered, which can form the mildly recycled pulsars ($P_{\rm spin}\sim20\,$ms) in DNS systems.
Individual subpulses of pulsars are regarded as the basic emission components, providing invaluable information to understand the radio emission process in the pulsar magnetosphere. Nevertheless, subpulses are overlapped with each other along the rotation phase for most pulsars, making it difficult to study the statistical properties of subpulses. Among the pulsars observed by the Five-hundred-meter Aperture Spherical radio Telescope, PSR B1916+14 has a large number of isolated well-resolved subpulses in the high time resolution observations, having a typical width of 0.15 ms and a high linear polarization. We find that the number distribution of subpulses contributes dominantly to the mean profile. According to the emission geometry, these emission units come from a region roughly 155 km above the polar cap in the pulsar magnetosphere, and the length scale of basic emission units is approximately 120 m. The deviations of polarization position angles for these single subpulses from the standard S-shaped curve are closely related to their fractional linear and circular polarization, and the large deviations tend to come from drifting subpulses.
Similarity solutions to the nonlinear non-equilibrium Marshak wave problem with a time dependent radiation driving source are presented. The radiation transfer model used is the gray, non-equilibrium diffusion approximation in the supersonic regime. These solutions constitute an extension of existing non-equilibrium supersonic Marshak wave solutions which are linear, to the nonlinear regime, which prevails in realistic high energy density systems. The generalized solutions assume a material model with power law temperature dependent opacities and a material energy density which is proportional to the radiation energy density, as well as a surface radiation temperature drive which obeys a temporal power-law. The solutions are analyzed in detail and it is shown that they take various qualitatively different forms according to the values of the opacity exponents. The solutions are used to construct a set of standardized benchmarks for supersonic non-equilibrium radiative heat transfer, which are nontrivial but straightforward to implement. These solutions are compared in detail to implicit Monte-Carlo and discrete-ordinate transport simulations as well gray diffusion simulations, showing a good agreement, which demonstrates the usefulness of these solutions as a code verification test problem.
A search for pulsed radiation at a frequency of 111 MHz in the direction of 116 RRAT candidates was carried out. For the search, archival data obtained on a meridian 128-beam radio telescope, a Large Phased Array (LPA), was used. For each candidate, about six days of observations were accumulated over an interval of eight years. Eleven new RRATs have been discovered. It was possible to estimate periods for six of them, and to construct average profiles for four of them. Some of the candidates turned out to be known pulsars observed in the side lobes of the radio telescope and interference. For the part of the candidates could not find pulses with a signal-to-noise ratio of more than seven, and their nature remains unknown.
In this work, we analyze in detail the problem of piston driven shock waves in planar media. Similarity solutions to the compressible hydrodynamics equations are developed, for a strong shock wave, generated by a time dependent pressure piston, propagating in a non-homogeneous planar medium consisting of an ideal gas. Power law temporal and spatial dependency is assumed for the piston pressure and initial medium density, respectively. The similarity solutions are written in both Lagrangian and Eulerian coordinates. It is shown that the solutions take various qualitatively different forms according to the value of the pressure and density exponents. We show that there exist different families of solutions for which the shock propagates at constant speed, accelerates or slows down. Similarly, we show that there exist different types of solutions for which the density near the piston is either finite, vanishes or diverges. Finally, we perform a comprehensive comparison between the planar shock solutions and Lagrangian hydrodynamic simulations, by setting proper initial and boundary conditions. A very good agreement is reached, which demonstrates the usefulness of the analytic solutions as a code verification test problem.
So far no diffuse emissions in dwarf spheroidal satellites of the Milky Way have ever been observed. Given that dwarf galaxies are predominantly composed of Dark Matter, the discovery of these signals could offer valuable insights into understanding the nature of Dark Matter. We present "diffSph", a Python tool which in its present version provides fast predictions of such diffuse signals in radio frequencies. It also features a very comprehensive module for the computation of "J" and "D" factors that are relevant for indirect Dark Matter detection using gamma rays. Routines are coupled to parton-shower algorithms and Dark Matter halo mass functions from state-of-the-art kinematic fits. This code is also useful for testing generic hypotheses (not necessarily associated with any Dark Matter candidate) about the cosmic-ray electron/positron sources in the dwarf galaxies. The diffSph tool has already been employed in searches for diffuse signals from dwarf spheroidal galaxies using the LOw Frequency ARray (LOFAR).
This is the first in a collection of three papers introducing the science with an ultra-violet (UV) space telescope on an approximately 130~kg small satellite with a moderately fast re-pointing capability and a real-time alert communication system approved for a Czech national space mission. The mission, called Quick Ultra-Violet Kilonova surveyor - QUVIK, will provide key follow-up capabilities to increase the discovery potential of gravitational wave observatories and future wide-field multi-wavelength surveys. The primary objective of the mission is the measurement of the UV brightness evolution of kilonovae, resulting from mergers of neutron stars, to distinguish between different explosion scenarios. The mission, which is designed to be complementary to the Ultraviolet Transient Astronomy Satellite - ULTRASAT, will also provide unique follow-up capabilities for other transients both in the near- and far-UV bands. Between the observations of transients, the satellite will target other objects described in this collection of papers, which demonstrates that a small and relatively affordable dedicated UV-space telescope can be transformative for many fields of astrophysics.
Searches for gravitational waves from compact-binary mergers, which to date have reported $\sim100$ observations, have previously ignored binaries whose components are both consistent with the mass of neutron stars $(1 M_\odot$ to $ 2 M_\odot)$ and have high dimensionless spin $>0.05$. While previous searches targeted sources that are representative of observed neutron star binaries in the galaxy, it is already known that neutron stars can regularly be spun up to a dimensionless spin of $\sim0.4$, and in principle reach up to $\sim0.7$ before breakup would occur. Furthermore, there may be primordial black hole binaries or exotic formation mechanisms to produce light black holes. In these cases, it is possible for the binary constituent to be spun up beyond that achievable by a neutron star. A single detection of this type of source would reveal a novel formation channel for compact-binaries. To determine if there is evidence for any such sources, we use PyCBC to conduct a targeted search of LIGO and Virgo data for light compact objects with high spin. Our analysis detects previously known observations GW170817 and GW200115; however, we report no additional mergers. The most significant candidate, not previously known, is consistent with the noise distribution, and so we constrain the merger rate of spinning light binaries.
A long-lived magnetar, potentially originating from a binary neutron star system, has been proposed to explain the extended emission observed in certain short-duration gamma-ray bursts (sGRBs), and is posited as a potential central engine to power the engine-fed kilonovae. Previously, the process by which energy is injected into the surrounding ejecta/jet was widely believed to be nearly isotropic. In this study, we employ special relativity magnetohydrodynamic (SRMHD) simulations to investigate the wind injection process from a magnetar central engine. We explore the dynamics and energy distribution within the system and found that the parameter $\alpha=u_{\rm A}/u_{\rm MWN}$ can be used to indicate the collimation of the magnetar wind energy injection, where $u_{\rm A}$ is the local Alfven four-speed and $u_{\rm MWN}$ is the four-speed of the magnetar wind nebular (MWN) formed from wind-ejecta collision. A significant portion of the injected energy from the magnetar spin-down wind will be channeled to the jet axis due to collimation within the MWN. Achieving isotropic energy injection requires a significantly small $\alpha$ that necessitates either an ultra-relativistic expanding MWN or an extremely low magnetization MWN, both of which are challenging to attain in sGRBs. Consequently, a considerably reduced energy budget (i.e. energy per solid angle reduced by a factor of up to 10 with respect to the value under isotropic assumption) is anticipated to be injected into the ejecta for engine-fed kilonovae. Engine-fed kilonovae would appear fainter than originally anticipated.
Compact radio AGN are thought to be young radio active galactic nuclei (AGN) at the early stage of AGN evolution, thus are ideal laboratory to study the high-energy emission throughout the evolution of radio AGN. In this work, we report for the first time the detection of the high-energy cutoff ($E_{\rm cut}$), a direct indicator of thermal coronal radiation, of X-ray emission in Mrk 348 ($z$ = 0.015), a young radio galaxy classified as compact symmetric object. With a 100 ks NuSTAR exposure, we find that the high-energy cutoff ($E_{\rm cut}$ ) is firmly detected ($218^{+124}_{-62}$ keV). Fitting with various Comptonization models indicates the presence of a hot corona with temperature $kT_{\rm e}$ = 35 -- 40 keV. These strongly support the corona origin for its hard X-ray emission. The comparison in the $E_{\rm cut}$ -- spectra index $\Gamma$ plot of Mrk 348 with normal large-scale radio galaxies (mostly FR II) yields no difference between them. This suggests the corona properties in radio sources may not evolve over time (i.e., from the infant stage to mature stage), which is to-be-confirmed with future sample studies of young radio AGN.
Complex organic molecules (COMs) have been detected ubiquitously in protostellar systems. However, at shorter wavelengths (~0.8mm) it is more difficult to detect larger molecules than at longer wavelengths (~3mm) because of the increase of millimeter dust opacity, line confusion, and unfavorable partition function. We aim to search for large molecules (>8 atoms) in the ALMA Band 3 spectrum of IRAS 16293-2422 B. We search for more than 70 molecules and identify as many lines as possible in the spectrum. The spectral settings were set to specifically target three-carbon species such as propanol and glycerol. We identify lines of 31 molecules including many oxygen-bearing COMs such as CH3OH and c-C2H4O and a few nitrogen- and sulfur-bearing ones such as HOCH2CN and CH3SH. The largest detected molecules are gGg-(CH2OH)2 and CH3COCH3. We do not detect glycerol or propanol but provide upper limits for them which are in line with previous laboratory and observational studies. The line density in Band 3 is only ~2.5 times lower in frequency space than in Band 7. From the detected lines in Band 3 at a $\gtrsim 6\sigma$ level, ~25-30% of them could not be identified indicating the need for more laboratory data of rotational spectra. We find similar column densities and column density ratios of COMs (within a factor ~2) between Band 3 and Band 7. The effect of dust optical depth for IRAS 16293-2422 B at an off-source location on column densities and column density ratios is minimal. Moreover, for warm protostars, long wavelength spectra are not only crowded, but also take longer integration times to reach the same sensitivity limit. The 3mm search has not yet resulted in detection of larger and more complex molecules in warm sources. A full deep ALMA Band 2-3 (i.e., 3-4 mm) survey is needed to assess whether low frequency data have the potential to reveal more complex molecules in warm sources.
Sub-mm surveys toward overdense regions in the early Universe are essential to uncover the obscured star-formation and the cold gas content of assembling galaxies within massive dark matter halos. In this work, we present deep ALMA mosaic observations covering an area of $\sim 2'\times2'$ around MQN01 (MUSE Quasar Nebula 01), one of the largest and brightest Ly-$\alpha$ emitting nebulae discovered thus far surrounding a radio-quiet quasar at $z\simeq3.25$. Our observations target the 1.2- and the 3-mm dust continuum, as well as the carbon monoxide CO(4-3) transition in galaxies in the vicinity of the quasar. We identify a robust sample of eleven CO line-emitting galaxies (including a closely-separated quasar companion) which lie within $\pm 4000\,{\rm km\,s^{-1}}$ relatively to the quasar systemic redshift. A fraction of these objects are missed in previous deep rest-frame optical/UV surveys thus highlighting the critical role of (sub-)mm imaging. We also detect a total of eleven sources revealed in their 1.2-mm dust continuum with six of them having either high-fidelity spectroscopic redshift information from rest-frame UV metal absorptions, or CO line which place them in the same narrow redshift range. A comparison of the CO luminosity function (LF) and 1.2-mm number count density with that of the general fields points to a galaxy overdensity of $\delta > 10$. We find evidence of a systematic flattening at the bright-end of the CO LF with respect to the trend measured in blank fields. Our findings reveal that galaxies in dense regions at $z\sim3$ are more massive and significantly richer in molecular gas than galaxies in fields, hence enabling a faster and accelerated assembly. This is the first of a series of studies to characterize one of the densest regions of the Universe found so far at $z > 3$.
Observations indicate dust populations vary between galaxies and within them, suggesting a complex life cycle and evolutionary history. Here we investigate the evolution of galactic dust populations across cosmic time using a suite of cosmological zoom-in simulations from the Feedback in Realistic Environments (FIRE) project, spanning $M_{\rm vir}=10^{9-12}M_{\odot};\,M_{*}=10^{6-11}\,M_{\odot}$. Our simulations incorporate a dust evolution model that accounts for the dominant sources of dust production, growth, and destruction and follows the evolution of specific dust species with set chemical compositions. All galactic dust populations in our suite exhibit similar evolutionary histories, with gas-dust accretion being the dominant producer of dust mass for all but the most metal-poor galaxies. The onset of efficient gas-dust accretion occurs above a `critical' metallicity threshold ($Z_{\rm crit}$). Due to this threshold, our simulations reproduce observed trends between galactic D/Z and metallicity and element depletion trends in the ISM. Furthermore, $Z_{\rm crit}$ varies between dust species due to differences in key element abundances, dust physical properties, and life cycle processes resulting in $Z_{\rm crit} \sim 0.05 Z_{\odot},\,0.2 Z_{\odot},\,0.5 Z_{\odot}$ for metallic iron, silicates, and carbonaceous dust, respectively. These variations could explain the lack of small carbonaceous grains observed in the Magellanic Clouds. We also find a delay between the onset of gas-dust accretion and when a dust population reaches equilibrium, which we call the equilibrium timescale ($\tau_{\rm eq}$). The relation between $\tau_{\rm eq}$ and the metal enrichment timescale of a galaxy, determined by its recent evolutionary history, can contribute to the scatter in the observed relation between galactic D/Z and metallicity.
Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to the cold gas decrease. In the first paper we showed that the dust removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide (CO) and 21 cm hydrogen (H I) line observations of these galaxies and measure the timescale of removal of the cold interstellar medium (ISM). We find that all the cold ISM components (dust, molecular and atomic gas) decline at similar rates. This allows us to rule out a wide range of potential ISM removal mechanisms (including starburst-driven outflows, astration, a decline in the number of asymptotic giant branch stars), and artificial effects like stellar mass-age correlation, environmental influence, mergers, and selection bias, leaving ionization by evolved low-mass stars and ionization/outflows by supernovae Type Ia or active galactic nuclei as viable mechanisms. We also provide evidence for an internal origin of the detected ISM. Moreover, we find that the quenching of star formation in these galaxies cannot be explained by a reduction in gas amount alone, because the star formation rates (SFRs) decrease faster (on a timescale of about 1.8 Gyr) than the amount of cold gas. Furthermore, the star formation efficiency of the ETGs (SFE = SFR/MH2) is lower than that of star-forming galaxies, whereas their gas mass fractions (fH2 = MH2/M*) are normal. This may be explained by the stabilization of gas against fragmentation, for example due to morphological quenching, turbulence, or magnetic fields.
Young terrestrial worlds are critical test beds to constrain prevailing theories of planetary formation and evolution. We present the discovery of HD 63433d - a nearby (22pc), Earth-sized planet transiting a young sunlike star (TOI-1726, HD 63433). HD 63433d is the third planet detected in this multiplanet system. The kinematic, rotational, and abundance properties of the host star indicate that it belongs to the young (414 $\pm$ 23 Myr) Ursa Major moving group, whose membership we update using new data from Gaia DR3 and TESS. Our transit analysis of the TESS light curves indicates that HD 63433 d has a radius of 1.1 $R_\oplus$ and closely orbits its host star with a period of 4.2 days. To date, HD 63433 d is the smallest confirmed exoplanet with an age less than 500 Myr, and the nearest young Earth-sized planet. Furthermore, the apparent brightness of the stellar host (V $\approx$ 6.9 mag) makes this transiting multiplanet system favorable to further investigations, including spectroscopic follow-up to probe atmospheric loss in a young Earth-sized world.
As the closest major galaxy merger and home to thousands of super star clusters (SSCs), the Antennae Galaxies (NGC 4038 and NGC 4039) are an important location to study the molecular clouds at sites of vigorous star formation. We cataloged giant molecular clouds (GMCs) in the region where the two galaxies overlap using high-resolution (~0.1" ~10 pc) Atacama Large Millimeter/submillimeter Array (ALMA) observations of the 12CO(2-1) and 13CO(2-1)} emission lines. Of the 72 individual GMCs identified in the overlap region, 17 are within uncertainties of having the necessary mass, pressure, and size needed to form super star clusters (SSCs). Of those 17 GMCs, only one has significant ionizing radiation, indicating that the birth environments are likely still intact in the 16 other GMCs. We compared the physical properties calculated from 12CO(2-1) GMC data with observations of 10 other galaxies obtained using the same emission line and similar resolution. Compared to other sources in this sample, the GMCs from the Antennae, as well as in other starbursts and in the centers of galaxies, have the highest luminosities, surface densities, and turbulent pressures. The GMCs in starbursts and at the centers of galaxies also have large linewidths, although the linewidths in the Antennae are among the widest. These comparative results also indicate that the Antennae GMCs have the highest virial parameters despite their high densities.
Using James Webb Space Telescope near-infrared data of the inner Orion Nebula, \citet{Pearson_McCaughrean_2023} detected 40 Jupiter-Mass Binary Objects (JuMBOS). These systems are not associated with stars and their components have masses of giant Jupiter-like planets and separations in the plane of the sky of order $\sim$100 au. The existence of these wide free-floating planetary mass binaries was unexpected in our current theories of star and planet formation. Here we report the radio continuum (6.1 and 10.0 GHz) Karl G.\ Jansky Very Large Array detection of a counterpart to JuMBO\,24. The radio emission appears to be steady at a level of $\sim$50 $\mu$Jy over timescales of days and years. We set an upper limit of $\simeq15$~km~s$^{-1}$ to the velocity of the radio source in the plane of the sky. As in the near-infrared, the radio emission seems to be coming from both components of the binary.
Massive star-forming galaxies in the high-redshift universe host large reservoirs of cold gas in their circumgalactic medium (CGM). Traditionally, these reservoirs have been linked to diffuse H I Lyman-$\alpha$ (Ly$\alpha)$ emission extending beyond $\approx 10$ kpc scales. In recent years, millimeter/submillimeter observations are starting to identify even colder gas in the CGM through molecular and/or atomic tracers such as the [C II] $158\,\mu$m transition. In this context, we study the well-known J1000+0234 system at $z=4.54$ that hosts a massive dusty star-forming galaxy (DSFG), a UV-bright companion, and a Ly$\alpha$ blob. We combine new ALMA [C II] line observations taken by the CRISTAL survey with data from previous programs targeting the J1000+0234 system, and achieve a deep view into a DSFG and its rich environment at a 0.2" resolution. We identify an elongated [C II]-emitting structure with a projected size of 15 kpc stemming from the bright DSFG at the center of the field, with no clear counterpart at any other wavelength. The plume is oriented $\approx 40^{\circ}$ away from the minor axis of the DSFG, and shows significant spatial variation of its spectral parameters. In particular, the [C II] emission shifts from 180 km/s to 400 km/s between the bottom and top of the plume, relative to the DSFG's systemic velocity. At the same time, the line width starts at 400-600 km/s but narrows down to 190 km/s at top end of the plume. We discuss four possible scenarios to interpret the [C II] plume: a conical outflow, a cold accretion stream, ram pressure stripping, and gravitational interactions. While we cannot strongly rule out any of these with the available data, we disfavor the ram pressure stripping scenario due to the requirement of special hydrodynamic conditions.
Recent deep and wide radio surveys extend the studies for radio-excess active galactic nuclei (radio-AGNs) to lower luminosities and higher redshifts, providing new insights into the abundance and physical origin of radio-AGNs. Here we focus on the cosmic evolution, physical properties and AGN-host galaxy connections of radio-AGNs selected from a sample of ~ 500,000 galaxies at 0 < z < 4 in GOODS-N, GOODS-S, and COSMOS fields. Combining deep radio data with multi-band, de-blended far-infrared (FIR) and sub-millimeter data, we identify 1162 radio-AGNs through radio excess relative to the FIR-radio relation. We study the cosmic evolution of 1.4 GHz radio luminosity functions (RLFs) for star-forming galaxies (SFGs) and radio-AGNs, which are well described by a pure luminosity evolution of $L_*\propto (1+z)^{-0.31z+3.41}$ and a pure density evolution of $\Phi_*\propto (1+z)^{-0.80z+2.88}$, respectively. We derive the turnover luminosity above which the number density of radio-AGNs surpasses that of SFGs. This crossover luminosity increases as increasing redshift, from $10^{22.9}$ W Hz$^{-1}$ at z ~ 0 to $10^{25.2}$ W Hz$^{-1}$ at z ~ 4. At full redshift range (0 < z < 4), we further derive the probability ($p_{radio}$) of SFGs and quiescent galaxies (QGs) hosting a radio-AGN as a function of stellar mass ($M_*$), radio luminosity ($L_R$), and redshift (z), which yields $p_{radio}\propto (1+z)^{3.54}M_*^{1.02}L_R^{-0.90}$ for SFGs, and $p_{radio}\propto (1+z)^{2.38}M_*^{1.39}L_R^{-0.60}$ for QGs, respectively. It indicates that radio-AGNs in QGs prefer to reside in more massive galaxies with larger $L_R$ than those in SFGs, and radio-AGN fraction increases towards higher redshift in both SFGs and QGs with a more rapid increase in SFGs. Further, we find that the radio-AGN fraction depends on accretion states of BHs and redshift in SFGs, while in QGs it also depends on BH (or galaxy) mass.
The JWST North Ecliptic Pole (NEP) Time Domain Field (TDF) is a $>$14 arcmin diameter field optimized for multi-wavelength time-domain science with JWST. Its location within JWST's northern continuous viewing zone offers optimal conditions for time-domain studies with JWST, ensuring year-round observability, absence of bright stars, and minimal Zodiacal foreground interference. It has been observed across the electromagnetic spectrum both from the ground and from space, including with the Hubble Space Telescope (HST). As part of HST observations over 3 cycles (the "TREASUREHUNT" program), deep images were obtained with ACS/WFC in F435W and F606W that cover almost the entire JWST NEP TDF. Many of the individual pointings of these programs partially overlap, allowing an initial assessment of the potential of this field for time-domain science with HST and JWST. The cumulative area of overlapping pointings is ~88 arcmin$^2$, with time intervals between individual epochs that range between 1 day and 4$+$ years. We present the discovery of 12 transients and ~100 variable sources to a depth of $m_{\rm AB} \simeq$ 29.5 mag (F606W). The majority of the transients will be supernovae, although at least two are likely quasars. Most variable sources are AGN, where we find ~0.35% (0.04%) of the general $z < 6$ field galaxy population to vary at the 3$\sigma$ (5$\sigma$) level. Based on a 5-year timeframe, this translates into a random supernova areal density of up to ~0.07 transients per arcmin$^2$ (~245 deg$^{-2}$) per epoch, and a variable AGN areal density of ~1.4 variables per arcmin$^2$ (~5184 deg$^{-2}$) to these depths.
We present results from the analysis of 88 carbon stars selected from Hamburg/ESO (HES) survey using low-resolution spectra (R$\sim$1330 \& 2190). The spectra were obtained with the Himalayan Faint Object Spectrograph Camera (HFOSC) attached to the 2-m Himalayan Chandra Telescope (HCT). Using a well-defined spectral criteria based on the strength of carbon molecular bands, the stars are classified into different groups. In our sample, we have identified 53 CH stars, four C-R stars, and two C-N type stars. Twenty-nine stars could not be classified due to the absence of prominent C$_{2}$ molecular bands in their spectra. We could derive the atmospheric parameters for 36 stars. The surface temperature is determined using photometric calibrations and synthesis of the H-alpha line profile. The surface gravity log g estimates are obtained using parallax estimates from the Gaia DR3 database whenever possible. Microturbulent velocity ($\zeta$) is derived using calibration equation of log g \& ${\zeta}$. We could determine metallicity for 48 objects from near-infrared Ca II triplet features using calibration equations. The derived metallicity ranges from $-$0.43$\leq$[Fe/H]$\leq$$-$3.49. Nineteen objects are found to be metal-poor ([Fe/H] $\leq$$-$1), 14 very metal-poor ([Fe/H]$\leq$$-$2), and five extremely metal-poor ([Fe/H]$\leq$$-$3.0) stars. Eleven objects are found to have a metallicity in the range $-$0.43 $\leq$[Fe/H]$\leq$$-$0.97. We could derive the carbon abundance for 25 objects using the spectrum synthesis calculation of the C$_{2}$ band around 5165\AA. The most metal-poor objects found will make important targets for follow-up detailed chemical composition studies based on high-resolution spectroscopy, that are likely to provide insight into the Galactic chemical evolution.
The satellite galaxy Crater II of the Milky Way is extremely cold and exceptionally diffuse. These unusual properties are challenging to understand in the standard model of cold dark matter. We investigate the formation of Crater II in self-interacting dark matter (SIDM), where dark matter particles can scatter and thermalize. We conduct a series of controlled N-body simulations to model the tidal evolution of Crater II, varying the self-interacting cross section, orbit parameters, and initial stellar distribution. Dark matter self-interactions lead to halo core formation and the distribution of stars expands accordingly. A cored SIDM halo also boosts tidal mass loss, allowing for a high orbit. Our simulations show that SIDM halos with a $1~{\rm kpc}$ core can simultaneously explain the low stellar velocity dispersion and the large half-light radius of Crater II, remaining robust to the initial distribution of stars. For the orbit motivated by the measurements from Gaia Early Data Release 3, the favored self-interacting cross section is approximately $60~{\rm cm^2/g}$ on the mass scale of Crater II.
We present an analysis of the outer Galaxy giant molecular filament (GMF) G214.5-1.8 (G214.5) using IRAM 30m data of $^{12}$CO, $^{13}$CO and C$^{18}$O. We find that the $^{12}$CO (1-0) and (2-1) derived excitation temperatures are near identical and are very low, with a median of 8.2 K, showing that the gas is extremely cold across the whole cloud. Investigating the abundance of $^{13}$CO across G214.5, we find that there is a significantly lower abundance along the entire 13 pc spine of the filament, extending out to a radius of $\sim 0.8$ pc, corresponding to $A_v \gtrsim 2$ mag and $T_{dust} \lesssim 13.5$ K. Due to this, we attribute the decrease in abundance to CO freeze-out, making G214.5 the largest scale example of freeze-out yet. We construct an axisymmetric model of G214.5's $^{13}$CO volume density considering freeze-out and find that to reproduce the observed profile significant depletion is required beginning at low volume densities, $n\gtrsim2000$ cm$^{-3}$. Freeze-out at this low number density is possible only if the cosmic-ray ionisation rate is $\sim 1.9 \times 10^{-18}$ s$^{-1}$, an order of magnitude below the typical value. Using timescale arguments, we posit that such a low ionisation rate may lead to ambipolar diffusion being an important physical process along G214.5's entire spine. We suggest that if low cosmic-ray ionisation rates are more common in the outer Galaxy, and other quiescent regions, cloud-scale CO freeze-out occurring at low column and number densities may also be more prevalent, having consequences for CO observations and their interpretation.
The spatial distribution of Galactic stars with different chemical abundances encodes information on the processes that drove the formation and evolution of the Milky Way. Survey selection functions are indispensable for analysing astronomical catalogues produced by large-scale surveys. The use of these selection functions in data modelling is more complex when data from different surveys are to be modelled simultaneously. We introduce a procedure for constructing the selection function of a sample of red clump stars that have parallaxes and elemental abundances from the Gaia mission. We separately constructed the selection function of the APOGEE DR17 red clump stars, which depends on very different observables and has a very different spatial coverage. We combined the two surveys and accounted for their joint selection function to provide strong constraints on the radial and vertical density distribution of mono-abundance populations, with Gaia offering a dense coverage of the solar neighbourhood, while APOGEE reaches larger distances near the Galactic plane. We confirm that the radial density profile steepens with increasing metallicity. The combined sample also indicates a metallicity-dependent flaring of the alpha-poor disc. We provide the code for constructing the Gaia selection function we used in this study through the GaiaUnlimited Python package.
We observe the magnetic field morphology towards a nearby star-forming filamentary cloud, G202.3+2.5, by the JCMT/POL-2 850 {\mu}m thermal dust polarization observation with an angular resolution of 14.4" (~0.053 pc). The average magnetic field orientation is found to be perpendicular to the filaments while showing different behaviors in the four subregions, suggesting various effects from filaments' collision in these subregions. With the kinematics obtained by N2H+ observation by IRAM, we estimate the plane-of-sky (POS) magnetic field strength by two methods, the classical Davis-Chandrasekhar-Fermi (DCF) method and the angular dispersion function (ADF) method, B_{pos,dcf} and B_{pos,adf} are ~90 {\mu}G and ~53 {\mu}G. We study the relative importance between the gravity (G), magnetic field (B) and turbulence (T) in the four subregions, find G > T > B, G >= T > B, G ~ T > B and T > G > B in the north tail, west trunk, south root and east wing, respectively. In addition, we investigate the projection effect on the DCF and ADF methods based on a similar simulation case and find the 3D magnetic field strength may be underestimated by a factor of ~3 if applying the widely-used statistical B_{pos}-to-B_{3D} factor when using DCF or ADF method, which may further underestimate/overestimate related parameters.
Massive stars condition the evolution of the interstellar medium by the amount of energy released during their lives and especially by their deaths as supernova explosions. The vast amounts of spectroscopic data for massive stars provided by previous and existing instruments on ground-based and space-based telescopes have already saturated our capability to process them by the use of human routines. As a consequence, there is a pressing need for machine-assisted tools to help handle incoming data. To this end, we present the development of a massive star spectroscopic multiwavelength interactive database designed for scientific research and a fully automatic stellar parameter determination tool. Here we show the preliminary results of the application of these tools to optical spectra of O-type stars.
In this work, we revisit the relationship between [O III] line width $w_{\rm 90}$ (as the indicator of AGN outflow velocity) and the radio emission in RQQs by employing a large sample of Type I quasars ($\sim 37,000$) selected from the Sloan Digital Sky Survey (SDSS) Data Release Sixteen. By median stacking the radio images (to include the dominant fraction of individually radio non-detected RQQs) of Karl G. Jansky Very Large Array (VLA) Sky Survey (VLASS) for subsamples of RQQs with different $w_{\rm 90}$, our study demonstrates that, the correlation between $w_{\rm 90}$ and radio emission in our SDSS RQQs is significant, and remains solid after controlling the effects of black hole mass, quasar luminosity, Eddington ratio and redshift. This intrinsic link supports that the [O III] outflows in quasars, most likely resulted from wide-angled sub-relativistic quasar winds launched from the accretion disc, could make a dominant contribution to radio emission in the general RQQs. Alternatively, the correlation may be attributed to low-power jets in RQQs if they are ubiquitous and could efficiently enhance the [O III] width through interacting with the ISM. Meanwhile, the star-formation rates traced by the flux ratio of [Ne V]/[O II] emission lines display no dependence on $w_{\rm 90}$ after controlling the effects of black hole mass, quasar luminosity, Eddington ratio and redshift. This suggests that the stronger radio emission in RQQs with larger $w_{\rm 90}$ could not be attributed to outflow enhanced (positive feedback) star formation in the hosts. However, this also indicates the outflows, though exhibiting robust correlation with radio power, produce neither positive nor negative feedback to the star formation in their hosts.
Radial profiles play a crucial role in the analysis and interpretation of astronomical data, facilitating the extraction of spatial information. However, highly customizable (for different scenarios) measurements over each elliptical annulus can be challenging. In response, we present 'astscript-radial-profile', which is part of Gnuastro from version 0.15 and has an extensive documentation. A convenient feature of this program is its capability to make the measurements with different operators (mean, median, sigma-clipping, and many more) over ellipses, very quickly and directly on the command-line with minimal dependencies. This research note is reproducible with Maneage, on the Git commit 104aad5.
We present a detailed view of cluster formation (CF) to trace the evolution and interaction history of the Magellanic Clouds (MCs) in the last 3.5 Gyr. Using the \textit{Gaia} DR3 data, we parameterized 1710 and 280 star clusters in the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), where 847 and 113 clusters are newly characterized in the outer LMC and SMC, respectively. We estimated the age-extinction-metallicity-distance parameters using an automated fitting of the color-magnitude diagram (CMD) after field star removal, followed by an MCMC technique. We report a first-time detection of two synchronized CF peaks in the MCs at 1.5$\pm$0.12 Gyr and 800$\pm$60 Myr. We recommend that the choice of the metallicity ($Z$) values of isochrones for clusters with age $\le$ 1 - 2 Gyr are Z$_{\text{LMC}}$ = 0.004 - 0.008 and Z$_{\text{SMC}}$ = 0.0016 - 0.004 for the LMC and SMC, respectively. We found evidence for spiral arms in the LMC, as traced by the cluster count profiles over the last 3.5 Gyr. The density maps provide evidence of ram-pressure stripping in the North-East of the LMC, a severe truncation of CF in the South of the LMC, and a radial shrinkage of CF in the SMC in the last 450 Myr. The last SMC-LMC interaction ($\sim$ 150 Myr) resulted in a substantial CF in the North and Eastern SMC, with a marginal impact on the LMC. This study provides important insights into the CF episodes in the MCs and their connection to the LMC-SMC-MW interactions.
The relative importance of magnetic fields, turbulence, and gravity in the early phases of star formation is still not well understood. We report the first high-resolution dust polarization observations at 850 $\mu$m around the most massive clump, located at the hub of the Giant Molecular Cloud G148.24+00.41, using SCUBA-2/POL-2 at the James Clerk Maxwell Telescope. We find that the degree of polarization decreases steadily towards the denser portion of the cloud. Comparing the intensity gradients and local gravity with the magnetic field orientations, we find that local gravity plays a dominant role in driving the gas collapse as the magnetic field orientations and gravity vectors seem to point towards the dense clumps. We also find evidence of U-shaped magnetic field morphology towards a small-scale elongated structure associated with the central clump, hinting at converging accretion flows towards the clump. Our observation has resolved the massive clump into multiple substructures. We study the magnetic field properties of two regions, central clump (CC) and northeastern elongated structure (NES). Using the modified Davis-Chandrasekhar Fermi method, we determine that the magnetic field strengths of CC and NES are $\sim$24.0 $\pm$ 6.0 $\mu$G and 20.0 $\pm$ 5.0 $\mu$G, respectively. The mass-to-flux ratios are found to be magnetically transcritical/supercritical, while the Alfv$\acute{\text{e}}$n Mach number indicates a trans-Alfv$\acute{\text{e}}$nic state in both regions. These results, along with Virial analysis, suggest that at the hub of G148.24+00.41, gravitational energy has an edge over magnetic and kinetic energies.
In this work, we compare star formation histories of massive (10.5 $< \log(\mathrm{M_*/M_{\odot}}) <$ 12) galaxies in the UniverseMachine model to those measured from the Large Early Galaxy Astrophysics Census (LEGA-C) at $0.6<z<1$. Following the LEGA-C study, we investigate how 50% ($t_{50}$) and 90% ($t_{90}$) formation timescales depend on total stellar mass. We find good agreement between the observed and model timescales for the star-forming population $\Delta\,t_{SF}\lesssim1\,\mathrm{Gyr}$ across the full mass range. In contrast, the observed age-mass correlation is weaker for the quiescent population compared to UniverseMachine models ($\Delta t_{Q}\lesssim2\,\mathrm{Gyr}$), especially at the high-mass end. This indicates continued star formation or additional processes in the most massive quiescent galaxies, a behavior not accounted for in the UniverseMachine model.
We present the second data release (DR2) of the Far-Infrared Polarimetric Large-Area CMZ Exploration (FIREPLACE) survey. This survey utilized the Stratospheric Observatory for Infrared Astronomy (SOFIA) High-resolution Airborne Wideband Camera plus (HAWC+) instrument at 214 $\mu$m (E-band) to observe dust polarization throughout the Central Molecular Zone (CMZ) of the Milky Way. DR2 consists of observations that were obtained in 2022 covering the region of the CMZ extending roughly from the Brick to the Sgr C molecular clouds (corresponding to a roughly 1$^{\circ}$ $\times$ 0.75$^{\circ}$ region of the sky). We combine DR2 with the first FIREPLACE data release covering the Sgr B2 region to obtain full coverage of the CMZ (a 1.5$^{\circ}$ $\times$0.75$^{\circ}$ region of the sky). After applying total and polarized intensity significance cuts on the full FIREPLACE data set we obtain $\rm\sim$65,000 Nyquist-sampled polarization pseudovectors. The distribution of polarization pseudovectors confirms a bimodal distribution in the CMZ magnetic field orientations, recovering field components that are oriented predominantly parallel or perpendicular to the Galactic plane. These magnetic field orientations indicate possible connections between the previously observed parallel and perpendicular distributions. We also inspect the magnetic fields toward a set of prominent CMZ molecular clouds (the Brick, Three Little Pigs, 50 km s$\rm^{-1}$, Circum-nuclear Disk, CO 0.02-0.02, 20 km s$\rm^{-1}$, and Sgr C), revealing spatially varying magnetic fields that generally trace the morphologies of the clouds. We find evidence that compression from stellar winds and shear from tidal forces are prominent mechanisms influencing the structure of the magnetic fields observed within the clouds.
Synchrotron emission is one of few observable tracers of galactic magnetic fields (\textbf{B}) and cosmic rays (CRs). Much of our understanding of \textbf{B} in galaxies comes from utilizing synchrotron observations in conjunction with several simplifying assumptions of equipartition models, however it remains unclear how well these assumptions hold, and what \textbf{B} these estimates physically represent. Using FIRE simulations which self consistently evolve CR proton, electron, and positron spectra from MeV to TeV energies, we present the first synthetic synchrotron emission predictions from simulated L$_{*}$ galaxies with "live" spectrally-resolved CR-MHD. We find that synchrotron emission can be dominated by relatively cool and dense gas, resulting in equipartition estimates of \textbf{B} with fiducial assumptions underestimating the "true" \textbf{B} in the gas that contributes the most emission by factors of 2-3 due to small volume filling factors. Motivated by our results, we present an analytic framework that expands upon equipartition models for estimating \textbf{B} in a multi-phase medium. Comparing our spectrally-resolved synchrotron predictions to simpler spectral assumptions used in galaxy simulations with CRs, we find that spectral evolution can be crucial for accurate synchrotron calculations towards galactic centers, where loss terms are large.
We present Herschel PACS spectroscopy of the [O III] 88.4um fine-structure line in the nearby WC8+O binary system gamma Vel to determine its oxygen abundance. The critical density of this line corresponds to several 10^5 R* such that it is spatially extended in PACS observations at the 336 pc distance to gamma Vel. Two approaches are used, the first involving a detailed stellar atmosphere analysis of gamma Vel using CMFGEN, extending to Ne ~ 10^0 cm^-3 in order to fully sample the line formation region of [O III] 88.4um. The second approach involves the analytical model introduced by Barlow et al. and revised by Dessart et al, additionally exploiting ISO LWS spectroscopy of [O III] 51.8um. We obtain higher luminosities for the WR and O components of gamma Vel with respect to De Marco et al, log L/L_sun = 5.31 and 5.56, respectively, due to the revised (higher) interferometric distance. We obtain an oxygen mass fraction of X_O = 1.0+/- 0.3% for an outer wind volume filling factor of f = 0.5+/-0.25, favouring either standard or slightly reduced Kunz et al. rates for the ^12C(alpha, gamma)^16O reaction from comparison with BPASS binary population synthesis models. We also revisit neon and sulphur abundances in the outer wind of gamma Vel from ISO SWS spectroscopy of [S IV] 10.5um [Ne II] 12.8um and [Ne III] 15.5um. The inferred neon abundance X_Ne = 2.0-0.6+0.4%, is in excellent agreement with BPASS predictions, while the.sulphur abundance of X_S = 0.04 +/- 0.01% agrees with the solar abundance, as expected for unprocessed elements.
We analyze the photometric data in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) over $\sim 1,200$ deg$^{2}$ to uncover new halo substructures beyond the distance, $D_{\odot}\sim$ 30 kpc, from the Sun. For this purpose, we develop an isochrone filter for an old, metal-poor stellar system to extract the faint main-sequence stars at a range of distances. With this method, we detect, not only the previously discovered substructures such as the Orphan Stream, but also the new overdensity toward Bo\"otes at about $D_{\odot}\sim$ 60 kpc and the new stream-like feature toward Pisces at around $D_{\odot}\sim$ 60 kpc. It has been suggested that a small-scale overdensity exists in this direction of Pisces (the so-called Pisces Overdensity), but our results show that the overdensity is widely spread with a tidally elongated feature. Combining our results with the ongoing Hyper Suprime-Cam narrow-band survey and the near-future spectroscopic survey with Prime Focus Spectrograph (PFS) will allow us to place strong constraints on the origin of these halo substructures.
Using data from ALFALFA, xGASS, HI-MaNGA and SDSS, we identify a sample of 47 "red but HI-rich"(RR) galaxies with $NUV-r > 5$ and unusually high HI-to-stellar mass ratios. We compare the optical properties and local environments between the RR galaxies and a control sample of "red and HI-normal"(RN) galaxies that are matched in stellar mass and color. The two samples are similar in the optical properties typical of massive red (quenched) galaxies in the local Universe. The RR sample tends to be associated with slightly lower density environments and has lower clustering amplitudes and smaller neighbor counts at scales from several $\times$100kpc to a few Mpc. The results are consistent with that the RR galaxies preferentially locate at the center of low-mass halos, with a median halo mass $\sim 10^{12}h^{-1}M_{\odot}$ compared to $\sim 10^{12.5}h^{-1}M_{\odot}$ for the RN sample. This result is confirmed by the SDSS group catalog which reveals a central fraction of 89% for the RR sample, compared to $\sim 60\%$ for the RN sample. If assumed to follow the HI size-mass relation of normal galaxies, the RR galaxies have an average HI-to-optical radius ratio of $R_{HI}/R_{90}\sim 4$, four times the average ratio for the RN sample. We compare our RR sample with similar samples in previous studies, and quantify the population of RR galaxies using the SDSS complete sample. We conclude that the RR galaxies form a unique but rare population, accounting for only a small fraction of the massive quiescent galaxy population. We discuss the formation scenarios of the RR galaxies.
We report the discovery of a previously uncatalogued arch-shaped filamentary nebula at the outer part of the Triangulum galaxy (M33) centred at R.A. = 1h34m25s, Dec = +30d20m17s (ICRS). This discovery stems from meticulous observations employing deep exposures of M33, using both H-alpha and [OIII] narrow-band filters. The nebula, designated as "Roig1 Prades Sky", exhibits an H-alpha surface brightness of 23.9 mag/arcsec2. Its sky projected location is 21 arcmin away from the M33 galactic centre towards the southeast direction with an extent of 120 by 440 pc. Deep spectroscopic observations are required to unveil its real nature.
We present the construction of a deep multi-wavelength PSF-matched photometric catalog in the UDS field following the final UKIDSS UDS DR11 release. The catalog includes photometry in 24 filters, from the MegaCam-uS (0.38 microns) band to the Spitzer-IRAC (8 microns) band, over 0.9 sq. deg. and with a 5-sigma depth of 25.3 AB in the K-band detection image. The catalog, containing approximately 188,564 (136,235) galaxies at 0.2 < z < 8.0 with stellar mass > 10$^{8}$ solar masses and K-band total magnitude K < 25.2 (24.3) AB, enables a range of extragalactic studies. We also provide photometric redshifts, corresponding redshift probability distributions, and rest-frame absolute magnitudes and colors derived using the template-fitting code eazy-py. Photometric redshift errors are less than 3 to 4 percent at z < 4 across the full brightness range in K-band and stellar mass range 10$^{8}$-10$^{12}$ solar masses. Stellar population properties (e.g., stellar mass, star-formation rate, dust extinction) are derived from the modeling of the spectral energy distributions (SEDs) using the codes FAST and Dense Basis.
In this work, we study deuterium fractionation in four starless cores in the low-mass star-forming region L1688 in the Ophiuchus molecular cloud. We study how the deuterium fraction ($R_D$) changes with environment, compare deuteration of ions and neutrals, core centre and its envelope, and attempt to reproduce the observed results with a gas-grain chemical model. We chose high and low gas density tracers to study both core centre and the envelope. With the IRAM 30m antenna, we mapped N$_2$H$^+$(1-0), N$_2$D$^+$(1-0), H$^{13}$CO$^+$ (1-0) and (2-1), DCO$^+$(2-1), and $p$-NH$_2$D(1$_{11}$-1$_{01}$) towards the chosen cores. The missing $p$-NH$_3$ and N$_2$H$^+$(1-0) data were taken from the literature. To measure the molecular hydrogen column density, dust and gas temperature within the cores, we used the Herschel/SPIRE dust continuum emission data, the GAS survey data (ammonia), and the COMPLETE survey data to estimate the upper limit on CO depletion. We present the deuterium fraction maps for three species towards four starless cores. Deuterium fraction of the core envelopes traced by DCO$^+$/H$^{13}$CO$^+$ is one order of magnitude lower ($\sim$0.08) than that of the core central parts traced by the nitrogen-bearing species ($\sim$0.5). Deuterium fraction increases with the gas density as indicated by high deuterium fraction of high gas density tracers and low deuterium fraction of lower gas density tracers and by the decrease of $R_D$ with core radii, consistent with the predictions of the chemical model. Our model results show a good agreement with observations for $R_D$(N$_2$D$^+$/N$_2$H$^+$) and R$_D$(DCO$^+$/HCO$^+$) and underestimate the $R_D$(NH$_2$D/NH$_3$).
We present a data reduction pipeline written in Python for data obtained with the near-infrared cross-dispersed echelle spectrograph, WINERED, which yields a 0.91$-$1.35 $\mu$m spectrum with the resolving power of $R_{\text{max}} \equiv \lambda / \Delta \lambda = 28,000$ or 70,000 depending on the observing mode. The pipeline was developed to efficiently extract the spectrum from the raw data with high quality. It comprises two modes: the calibration and the science mode. The calibration mode automatically produces the flat-fielding image, bad pixel map, echellogram distortion map and the dispersion solution from the set of the calibration data. Using calibration images and parameters, the science data of astronomical objects can be reduced automatically using the science mode. The science mode is also used for the real-time quick look at the data during observations. An example of the spectra reduced with WARP is presented. The effect of the highly inclined slit image on the spectral resolution is discussed.
The age and mass of red giants are essential for understanding the structure and evolution of the Milky Way. Traditional isochrone methods for these estimations are inherently limited due to overlapping isochrones in the Hertzsprung-Russell diagram, while asteroseismology, though more precise, requires high-precision, long-term observations. In response to these challenges, we developed a novel framework, Spectral Transformer (SPT), to predict the age and mass of red giants aligned with asteroseismology from their spectra. A key component of SPT, the Multi-head Hadamard Self-Attention mechanism, designed specifically for spectra, can capture complex relationships across different wavelength. Further, we introduced a Mahalanobis distance-based loss function to address scale imbalance and interaction mode loss, and incorporated Monte Carlo dropout for quantitative analysis of prediction uncertainty.Trained and tested on 3,880 red giant spectra from LAMOST, the SPT achieved remarkable age and mass estimations with average percentage errors of 17.64% and 6.61%, respectively, and provided uncertainties for each corresponding prediction. The results significantly outperform those of traditional machine learning algorithms and demonstrate a high level of consistency with asteroseismology methods and isochrone fitting techniques. In the future, our work will leverage datasets from the Chinese Space Station Telescope and the Large Synoptic Survey Telescope to enhance the precision of the model and broaden its applicability in the field of astronomy and astrophysics.
The radiation damage to a silicon photomultiplier (SiPM) set on a satellite orbit increases energy threshold for scintillator detectors. We confirmed that 1 krad of radiation increases the energy threshold by approximately a factor of 10, which is worst for our system. Using one or two SiPMs damaged by proton irradiation and a plastic scintillator, we performed the following three experiments in our attempt to lower the energy threshold of radiation-damaged SiPMs to the greatest extent: (1) measurements using a current waveform amplifier rather than a charge-sensitive amplifier, (2) coincidence measurements with two radiation-damaged SiPMs attached to one scintillator and summing up their signals, and (3) measurements at a low temperature. Our findings confirmed that the use of a current waveform amplifier, as opposed to a charge-sensitive amplifier and a shaping amplifier, could lower the energy threshold to approximately 65% (from 198 keV to 128 keV). Furthermore, if we set the coincidence width appropriately and sum up the signals of the two SiPMs in the coincidence measurement, the energy threshold could be lowered to approximately 70% (from 132 keV to 93 keV) with little loss of the acquired signal, compared to that of use of only one scintillator. Finally, if we perform our measurements at a temperature of -20 {\deg}C, we could lower the energy threshold to approximately 34% (from 128 keV to 43 keV) compared to that of at 20 {\deg}C. Accordingly, we conclude that the energy threshold can be lowered to approximately 15% by using a combination of these three methods.
We give conditions for an exoplanetary system to function as an ideal amusement park/vacation resort (with its separate parking lot, of course); in case of massive human interplanetary colonization. Our considerations stem from the fact that an amusement park needs a parking lot of roughly the same surface area, thus the best option for its construction would be a system with at least 2 planets close to each other for easy tourist transportation. We also discuss the likelihood of finding such a system out there to cut down on construction costs.
The visible universe is filled with different types of plasma media in the form of stars, nebulas and other forms of excited gases. These matter fields have a high influence on the gravity and are likely to be present around the black holes due to the immense gravitational attraction. Since a plasma medium affects the speed of light, therefore we investigated the null geodesics and various optical features around the rotating black hole in Kalb-Ramond gravity immersed in plasma medium. Various plasma distributions are considered to develop a comparative study for their influence on unstable null circular orbits, shadows and evaporation rate of the black hole in the presence of a plasma medium. Moreover, the shadow results are also compared with Event Horizon Telescope data for M78* and Sgr A* in order to estimate the parametric bounds for which the rotating black hole in Kalb-Ramond gravity is considered either M87* or Sgr A* under the different values of plasma parameters. From this analysis, we also found the distribution of plasma that has a significant impact on the above mentioned features and is most likely to be present around M87* and Sgr A*.
The residual gas damping of the test mass (TM) in the free molecular flow regime is studied in the finite open systems for high-precision gravity-related experiments. Through strict derivation, we separate the damping coefficients for two finite open systems, i.e., the bi-plate system and the sensor core system, into base damping and diffusion damping. This elucidates the relationship between the free damping in the infinite gas volume and the proximity damping in the constrained volume, unifies them into one microscopic picture, and allows us to point out three pathways of energy dissipation in the bi-plate gap. We also provide the conditions that need to be met to achieve this separation. In applications, for space gravitational wave detection, our results for the residual gas damping coefficient for the 4TM torsion balance experiment is the closest one to the experimental and simulation data compared to previous models. For the LISA mission, our estimation for residual gas acceleration noise at the sensitive axis is consistent with the simulation result, within about $5\%$ difference. In addition, in the test of the gravitational inverse-square law, our results suggest that the constraint on the distance between TM and the conducting membrane can be reduced by about $28\%$.
We test ideas of the recently proposed first-order thermodynamics of scalar-tensor gravity using an exact geometry sourced by a conformally coupled scalar field. We report a non-monotonic behaviour of the effective ``temperature of gravity'' not observed before and due to a new term in the equation describing the relaxation of gravity toward its state of equilibrium, i.e., Einstein gravity, showing a richer range of thermal behaviours of modified gravity than previously thought.
This paper discusses the gravitational collapse of dynamical self-gravitating fluid distribution in $f(\mathcal{R},\mathcal{T},\mathcal{Q})$ gravity, where $\mathcal{Q}=\mathcal{R}_{\varphi\vartheta}\mathcal{T}^{\varphi\vartheta}$. In this regard, we assume a charged anisotropic spherical geometry involving dissipation flux and adopt standard model of the form $\mathcal{R}+\Phi\sqrt{\mathcal{T}}+\Psi\mathcal{Q}$, where $\Phi$ and $\Psi$ symbolize real-valued coupling parameters. The Misner-Sharp as well as M\"{u}ler-Israel Stewart mechanisms are employed to formulate the corresponding dynamical and transport equations. We then interlink these evolution equations which help to study the impact of state variables, heat dissipation, modified corrections and charge on the collapse rate. The Weyl scalar is further expressed in terms of the modified field equations. The necessary and sufficient condition of conformal flatness of the considered configuration and homogeneous energy density is obtained by applying some constraints on the model along with disappearing charge and anisotropy. Finally, we discuss different cases to investigate how the spherical matter source is affected by the charge and modified corrections.
We present and analyze a new non-perturbative radiative solution of Horndeski gravity. This exact solution is constructed by a disformal mapping of a seed solution of the shift-symmetric Einstein-Scalar system belonging to the Robinson-Trautman geometry describing the gravitational radiation emitted by a time-dependent scalar monopole. After analyzing in detail the properties of the seed, we show that while the general relativity solution allows for a shear-free parallel transported (PT) null frame, the disformed solution can only admit parallel transported null frames with a non-vanishing shear. This result shows that, at the nonlinear level, the scalar-tensor mixing descending from the higher-order terms in Horndeski dynamics can generate shear out of a pure scalar monopole. We further confirm this analysis by identifying the spin-0 and spin-2 polarizations in the disformed solution using the Penrose limit of our radiative solution. Finally, we compute the geodesic motion and the memory effects experienced by two null test particles with vanishing initial relative velocity after the passage of the pulse. This exact radiative solution offers a simple framework to witness nonlinear consequences of the scalar-tensor mixing in higher-order scalar-tensor theories.
This article provides a concise introduction to Bartnik's quasi-local mass, and surveys a selection of results pertaining to the understanding of it. The aim is to serve as both an entry point to the topic, and a quick reference of results for those already familiar with it.
We study the phase structure of hyperscaling violating black holes using Lyapunov exponents. For describing hyperscaling violating system, we chose a particular gravity model constructed from generalized Einstein-Maxwell-Dilaton action which includes the Lifshitz cases in appropriate limit. We study the relationship between Lyapunov exponents and black hole phase transitions considering both the timelike and null geodesics. We observe that, the black hole phase transiton properties are reflected in Lyapunov exponent where its multiple branches correspond to the distinct phases of the black hole. The discontinuos change of the Lyapunov exponent during the phase transition serve as an order parameter with critical exponent $1/2$ near the critical point. Our numerical study reveals that the correlation between the Lyapunov exponent and black hole thermodynamic properties can be generalised beyond the AdS spacetime. We find that it is independent of the hyperscaling violation parameter as well as the Lifshitz exponent.
We study 4-dimensional asymptotically flat electrostatic electro-vacuum spacetimes with a connected black hole, photon sphere, or equipotential photon surface inner boundary. Our analysis, inspired by the potential theory approach by Agostiniani-Mazzieri, allows to give self-contained proofs of known uniqueness theorems of the sub-extremal, extremal and super-extremal Reissner-Nordstr\"om spacetimes. We also obtain new results for connected photon spheres and for connected photon surfaces in the extremal case. Finally, we provide, up to a restriction on the range of their radii, the uniqueness result for connected (both non-degenerate and degenerate) photon surfaces in the super-extremal case, not yet treated in the literature.
We demonstrate that the leptogenesis mechanisms, which are associated with B-L symmetry breaking mechanism has notable effects on the production of gravitational waves. These gravitational waves align well with the recent observations of a stochastic gravitational wave background by NANOGrav and pulsar-timing arrays (PTAs). For these gravitational waves to match the recent measurements, the critical value of the B-L breaking should be around the GUT scale. Moreover, we consider the generation of primordial gravitational waves from binary systems of Primordial Black Holes (PBHs) which could be predicted by the recent detection of gravitational waves. PBHs with specific masses can be responsible for massive galaxy formation observed at high redshifts reported by the James Webb Space Telescope (JWST). We contemplate the potential for a shared source between the NANOGrav and JWST observations, namely primordial black holes. These black holes could serve as seeds of rapid galaxy formation, offering an explanation for the galaxies observed by JWST.
We study the thermodynamic properties of the Friedmann-Robertson-Walker (FRW) universe in the brane world scenario, concentrating on the Randall-Sundrum II model. From the first law of thermodynamics for the FRW universe, we find that the work density W can be identified with the thermodynamic pressure P. We construct the equation of state P=P(V,T) for the FRW universe in the brane world scenario, which does not show P-V phase transition. We further study the Joule-Thomson expansion of the FRW universe, and derive the Joule-Thomson coefficient, which has an inversion point that is affected by the brane tension. These results could provide new ways to test the brane world scenario and extra dimension.
The Gibbons-Werner (GW) method is a powerful approach in studying the gravitational deflection of particles moving in curved spacetimes. The application of the Gauss-Bonnet theorem (GBT) to integral regions constructed in a two-dimensional manifold enables the deflection angle to be expressed and calculated from the perspective of geometry. However, different techniques are required for different scenarios in the practical implementation which leads to different GW methods. For the GW method for stationary axially symmetric (SAS) spacetimes, we identify two problems: (a) the integral region is generally infinite, which is ill-defined for some asymptotically nonflat spacetimes whose metric possesses singular behavior, and (b) the intricate double and single integrals bring about complicated calculation, especially for highly accurate results and complex spacetimes. To address these issues, a generalized GW method is proposed in which the infinite region is replaced by a flexible region to avoid the singularity, and a simplified formula involving only a single integral of a simple integrand is derived by discovering a significant relationship between the integrals in conventional methods. Our method provides a comprehensive framework for describing the GW method for various scenarios. Additionally, the generalized GW method and simplified calculation formula are applied to three different kinds of spacetimes--Kerr spacetime, Kerr-like black hole in bumblebee gravity, and rotating solution in conformal Weyl gravity. The first two cases have been previously computed by other researchers, affirming the effectiveness and superiority of our approach. Remarkably, the third case is newly examined, yielding an innovative result for the first time.
We study gauge theories and quantum gravity in a finite interval of time $\tau $, on a compact space manifold $\Omega $. The initial, final and boundary conditions are formulated in gauge invariant and general covariant ways by means of purely virtual extensions of the theories, which allow us to "trivialize" the local symmetries and switch to invariant fields (the invariant metric tensor, invariant quark and gluon fields, etc.). The evolution operator $U(t_{\text{f}},t_{\text{i}})$ is worked out diagrammatically for arbitrary initial and final states, as well as boundary conditions on $\partial \Omega $, and shown to be well defined and unitary for arbitrary $\tau =t_{\text{f}}-t_{\text{i}}<\infty $. We illustrate the basic properties in Yang-Mills theory on the cylinder.
The Swampland Distance Conjecture (SDC) states that, as we move towards an infinite distance point in moduli space, a tower of states becomes exponentially light with the geodesic distance in any consistent theory of Quantum Gravity. Although this fact has been tested in large sets of examples, it is fair to say that a bottom-up justification that explains both the geodesic requirement and the exponential behavior has been missing so far. In the present paper we address this issue by making use of the Covariant Entropy Bound as applied to the EFT. When applied to backgrounds of the Dynamical Cobordism type in theories with a moduli space, we are able to recover these main features of the SDC. Moreover, this naturally leads to universal lower and upper bounds on the 'decay rate' parameter $\lambda_{\text{sp}}$ of the species scale, that we propose as a convex hull condition under the name of Species Scale Distance Conjecture (SSDC). This is in contrast to already proposed universal bounds, that apply to the SDC parameter of the lightest tower. We also extend the analysis to the case in which asymptotically exponential potentials are present, finding a nice interplay with the asymptotic de Sitter conjecture. To test the SSDC, we study the convex hull that encodes the (asymptotic) moduli dependence of the species scale. In this way, we show that the SSDC is the strongest bound on the species scale exponential rate which is preserved under dimensional reduction and we verify it in M-theory toroidal compactifications.
The laser-interferometer space antenna (LISA) will be launched in the mid 2030s. It promises to observe the coalescence of massive black-hole (BH) binaries with signal-to-noise ratios (SNRs) reaching thousands. Crucially, it will detect some of these binaries with high SNR both in the inspiral and the merger-ringdown stages. Such signals are ideal for tests of General Relativity (GR) using information from the whole waveform. Here, we consider astrophysically motivated binary systems at the high-mass end of the population observable by LISA, and simulate their signals using the newly developed multipolar effective-one-body model: \texttt{pSEOBNRv5HM}. The merger-ringdown signal in this model depends on the binary properties, and also on parameters that describe fractional deviations from the GR quasi-normal-mode (complex) frequencies of the remnant BH. Performing full Bayesian analyses, we assess to which accuracy LISA will be able to constrain deviations from GR in the ringdown signal when using information from the whole signal. We find that these deviations can typically be constrained to within $10\%$ and in the best cases to within $1\%$. We also show that with this model we can measure the binary masses and spins with great accuracy even for very massive BH systems with low SNR in the inspiral. We also probe the accuracy of the \texttt{SEOBNRv5HM} waveform family by performing synthetic injections of GR numerical-relativity waveforms. Using a novel method that we develop here to quantify the impact of systematic errors, we show that already for sources with SNR $\mathcal{O}(100)$, we would measure erroneous deviations from GR due to waveform model inaccuracies. One of the main sources of error is the mismodelling of the relative alignment between harmonics. Our results confirm the need for improving waveform models to perform tests of GR with high SNR binary BHs observed by LISA.
A number of approaches to gravitation have much in common with the gauge theories of the standard model of particle physics. In this paper, we develop the Hamiltonian formulation of a class of gravitational theories that may be regarded as spontaneously-broken gauge theories of the complexified Lorentz group $SO(1,3)_C$ with the gravitational field described entirely by a gauge field valued in the Lie algebra of $SO(1,3)_C$ and a `Higgs field' valued in the group's fundamental representation. The theories have one free parameter $\beta$ which appears in a similar role to the inverse of the Barbero-Immirzi parameter of Einstein-Cartan theory. However, contrary to that parameter, it is shown that the number of degrees of freedom crucially depends on the value of $\beta$. For non-zero values of $\beta$, it is shown that three complex degrees of freedom propagate on general backgrounds, and for the specific values $\beta=\pm i$ an extension to General Relativity is recovered in a symmetry-broken regime. For the value $\beta=0$, the theory propagates no local degrees of freedom. A non-zero value of $\beta$ corresponds to the self-dual and anti-self-dual gauge fields appearing asymmetrically in the action, therefore in these models, the existence of gravitational degrees of freedom is tied to chiral asymmetry in the gravitational sector.
In this paper, we derive a soft photon theorem and a soft gluon theorem in the de Sitter spacetime from the Ward identity of the near cosmological horizon large gauge transformation. Taking the flat limit of the de Sitter spacetime, the soft theorems naturally recover the corresponding flat spacetime soft theorems.
In this paper, we study the gravitational memory effect in pp-wave spacetimes due to the passage of a pulse having the form of a ramp profile through this spacetime. We have analyzed the effect of this pulse on the evolution of nearby geodesics, and have determined analytical solutions of the geodesic equations in the Brinkmann coordinates. We have also examined the changes in the separation between a pair of geodesics and their velocity profiles. The separation (along $ x $ or $ y $-direction) increases monotonically from an initial constant value. In contrast, the relative velocity grows from zero and settles to a final non-zero constant value. These resulting changes are retained as memory after the pulse dies out. The nature of this memory is similar to that determined by earlier workers using Gaussian, square, and other pulse profiles, thereby validating the universality of gravitational wave memory.
We have investigated the motion for photons in the Kerr black hole spacetime under the axion-photon coupling. The birefringence phenomena arising from the axion-photon coupling can be negligible in the weak coupling approximation because the leading-order contributions to the equations of motion come from the square term of the coupling parameter. We find that the coupling parameter makes the size of shadows slightly increase for arbitrary spin parameter. For the rapid rotating black hole case with a larger coupling, we find that there exist a pedicel-like structure appeared in the left of the D-type like shadows.Comparing the shadow size of the Kerr black hole with the shadow size of the Sgr A* and M87* black holes, we find that there is room for such a theoretical model of the axion-photon coupling.
The effective low temperature dynamics of near-extremal black holes is governed by the quantum fluctuations of the Schwarzian mode of JT gravity. Utilizing as a proxy a planar charged black hole in asymptotically Anti-de-Sitter spacetime, we investigate the effects of these fluctuations on a probe scalar field. The corresponding holographic real-time boundary correlators are computed following a holographic renormalization procedure, using the dubbed gravitational Schwinger-Keldysh geometry (grSK) and known exact results of boundary correlators from the near-horizon region. This analysis gives rise to a retarded Green's function that decays as a power law for late Lorentzian times. Its analytic structure indicates the presence of a branch cut in the complex frequency domain at finite temperature. These features are a non-perturbative hallmark that prevails as long as the planar transverse space is kept compact.
In modular invariant models of flavor, observables must be modular invariant. The observables discussed so far in the literature are functions of the modulus $\tau$ and its conjugate, $\bar\tau$. We point out that certain combinations of observables depend only on $\tau$, i.e. are meromorphic, and in some cases even holomorphic functions of $\tau$. These functions, which we dub ``invariants'' in this Letter, are highly constrained, renormalization group invariant, and allow us to derive many of the models' features without the need for extensive parameter scans. We illustrate the robustness of these invariants in two existing models in the literature based on modular symmetries, $\Gamma_{3}$ and $\Gamma_{5}$. We find that, in some cases, the invariants give rise to robust relations among physical observables that are independent of $\tau$. Furthermore, there are instances where additional symmetries exist among the invariants. These symmetries are relevant phenomenologically and may provide a dynamical way to realize symmetries of mass matrices.
Baryon number is an accidental symmetry of the Standard Model (SM) Lagrangian that so far has been measured to be exactly preserved, although it is expected to be violated at higher energies. In this work we compute order-of-magnitude estimates for the matching contributions of generic ultraviolet models to effective operators that generate nucleon decay processes. This is done in a systematic and automated way using operators constructed from SM fields up to dimension nine and working in a framework that has proved useful in the study of lepton-number violation. For each of the operators we derive estimates for the rates of different nucleon-decay channels. These allow us to establish model-independent lower bounds on the underlying new-physics scale and identify potential correlations between the various decay modes. The results are most relevant for genuine models that do not generate nucleon decay at a lower order. This analysis is especially timely given the expected future sensitivities in numerous experiments such as Hyper-K, DUNE, JUNO and THEIA.
The emergence of hadron mass represents one of the most challenging and still open problems in contemporary hadron physics. The results on the nucleon resonance electroexcitation amplitudes available from the CLAS data on $\pi N$ and $\pi^+\pi^-p$ electroproduction analyzed within the continuum Schwinger method open up a new avenue for gaining insight into the strong interaction dynamics that are responsible for the generation of the dominant part of hadron mass. Future prospects of these studies in experiments of the 12-GeV era with CLAS12 and after a potential increase of the CEBAF energy up to 22 GeV will offer a unique opportunity to explore the full range of distances where the dominant part of hadron mass and $N^*$ structure emerge from QCD.
We conduct a systematic study of the electromagnetic properties of multiquark systems with undetermined internal structures. Motivated by the recent observation of the $T_{cc}^+$ state, we apply the light-cone version of the QCD sum rule method to extract the magnetic dipole moments of several possible doubly-charmed vector tetraquark states. When analyzing the magnetic dipole moment of these states, they are modeled to have the diquark-antidiquark configurations. The magnetic dipole moments for the members are extracted as $ \mu_{T_{cc \bar{u} \bar{d}}} = 1.17^{+0.44}_{-0.32} \, \mu_N$, $ \mu_{T_{cc \bar{u} \bar{s}}} = 1.35^{+0.50}_{-0.37} \, \mu_N$, $ \mu_{T_{cc \bar{d} \bar{s}}} = -2.69^{+1.02}_{-0.75} \, \mu_N$, $ \mu_{T_{cc \bar{u} \bar{u}}} = 1.33^{+0.56}_{-0.40} \, \mu_N$, $ \mu_{T_{cc \bar{d} \bar{d}}} = 1.41^{+0.57}_{-0.43} \, \mu_N$ and $ \mu_{T_{cc \bar{s} \bar{s}}} = 1.44^{+0.53}_{-0.41} \, \mu_N$. Comparing the results obtained for the magnetic dipole moments of the $T_{cc \bar{u} \bar{d}}$ state with the $T_{cc \bar{u} \bar{s}}$ state, the $U$-symmetry is seen to be broken at about $\%15$, while for the $T_{cc \bar{d} \bar{d}}$ and $T_{cc \bar{s} \bar{s}}$ states, this symmetry is minimally broken. The obtained results may be useful to determine the true nature of these new interesting states.
Low-scale leptogenesis is an attractive explanation for the observed baryon asymmetry of our universe that can be tested at a variety of laboratory experiments. In these proceedings, we review some recent advances in this field. In particular, we find that the viable parameter space is strongly enhanced, compared to the minimal case with two right-handed neutrinos, when a third generation is considered and explore the impact of such enhancement on the testability of the scenario. Finally, we also look at the impact of specific flavour and CP symmetries on said parameter space.
This presentation opens with a brief review of lattice QCD calculations showing the $2s$ radial excitation of the nucleon sits at approximately 2 GeV, well above the Roper resonance position. We then proceed to reconcile this observation with experimental scattering data. While the idea of dressing quark-model states in a coupled-channel analysis to describe scattering data has been around for decades, it's now possible to bring these descriptions to the finite-volume of lattice QCD for confrontation with lattice-QCD calculations. This combination of lattice QCD and experiment demands that we reconsider our preconceived notions about the quark-model and its excitation spectrum. We close with a discussion of an unanticipated resolution to the missing baryon resonances problem.
The well-known model of the triangle diagrams with $D^*\bar DD^*$ and $\bar D^*D\bar D^*$ mesons in the loops is compared with the modern data on the amplitude of the $X(3872)\to\pi^0\chi_{c1}(1P)$ decay. Considering the $X(3872)$ object as a $\chi_{c1}(2P)$ charmonium state, we introduce a parameter $\xi$ characterizing the scale of the isotopic symmetry violation in this decay and find a lower limit of $\xi\simeq0.0916$. The model incorporates the only fitted parameter associated with the form factor. We analyze in detail the influence of the form factor on the amplitude $X(3872)\to\pi^0 \chi_{c1}(1P)$ and on the parameter $\xi$. As the suppression of the amplitude by the form factor increases, $\xi$ increases. Due to the fact that the $X(3872)$ resonance is located practically at the threshold of the $D^0\bar D^{*0}$ channel, the amplitude of $X(3872) \to\pi^0\chi_{c1}(1P)$ turns out to be proportional to $\sqrt{m_d -m_u}$. Using the estimating values for the coupling constants $g_{XD\bar D^*}$, $g_{\chi_{ c1}D\bar D^*}$, and $g_{D^{*0}D^{*0}\pi^0}$, we show that the model of the triangle loop diagrams is in reasonable agreement with the available data. Apart from the difference in the masses of neutral and charged charmed mesons, any additional exotic sources of isospin violation in $X(3872)\to\pi^0\chi_{c1}(1P)$ (such as a significant difference between the coupling constants $g_{XD^0\bar D^{*0}}$ and $g_{XD^+ D^{*-}}$) are not required to interpret the data. This indirectly confirms the isotopic neutrality of the $X(3872)$, which is naturally realized for the $c\bar c$ state $\chi_{c1}(2P)$.
We take the Dyson-Schwinger Equation approach for the quark propagator at complex chemical potential for the $N_{f} = 2+1$ QCD. The phase transition line in the imaginary chemical potential region is computed, whose curvature is found to be consistent with the one at real chemical potential. Moreover, the computation in the complex chemical potential plane allows us to determine the location of the Lee-Yang edge singularities. We show explicitly that the critical end point coincides with the Lee Yang edge singularities on the real $\mu_{B}$ axis. We also discuss the possibility of extrapolating the CEP from the singularities within a certain range of chemical potential, and investigate the scaling behavior of the singularities.
Simulations of the $\Lambda$-hyperon and light-hypernuclei production in Au+Au collisions at $\sqrt{s_{NN}}=$ 3 GeV were performed within updated Three-fluid Hydrodynamics-based Event Simulator Extended by UrQMD (Ultra-relativistic Quantum Molecular Dynamics) final State interactions (THESEUS). The light (hyper)nuclei are treated thermodynamically, i.e. they are considered on the equal basis with hadrons. The only additional parameter is related to the late freeze-out that imitates the afterburner stage for the light (hyper)nuclei because the UrQMD is not able to dynamically treat them. The calculation of hypernuclei production is completely similar to that of light nuclei. The hypernuclei results are compared with recent STAR data. It is found that the calculated midrapidity $_\Lambda^3$H/$\Lambda$ ratio falls within the error bars of the experimental point. It is remarkable that large difference between the $t/p$ and $_\Lambda^3$H/$\Lambda$ ratios is reproduced without any additional parameters. Rapidity distributions of $_\Lambda^3$H/$\Lambda$ and $_\Lambda^4$He/$\Lambda$ ratios are predicted. Midrapidity mean transverse momenta of protons, $\Lambda$s and light (hyper)nuclei in central collisions well agree with the data. The calculated directed flow also reasonably well reproduces of the data.
Effective field theory (EFT) provides a model-independent framework for interpreting the results of dark matter (DM) direct detection experiments. In this study, we demonstrate that the two fermionic DM-quark tensor operators, $(\bar{\chi} i\sigma^{\mu\nu} \gamma^5 \chi) (\bar{q} \sigma_{\mu\nu}q)$ and $(\bar{\chi} \sigma^{\mu\nu} \chi) (\bar{q} \sigma_{\mu\nu} q)$, can contribute to the DM electric and magnetic dipole moments via nonperturbative QCD effects, in addition to the well-studied contact DM-nucleon operators. We then investigate the constraints on these two operators by considering both the contact and the dipole contributions using the XENON1T nuclear recoil and Migdal effect data. We also recast other existing bounds on the DM dipole operators, derived from electron and nuclear recoil measurements in various direct detection experiments, as constraints on the two tensor operators. For $m_\chi \lesssim 1\,\rm GeV$, our results significantly extend the reach of constraints on the DM-quark tensor operators to masses as low as $5\,\rm MeV$, with the bound exceeding that obtained by the Migdal effect with only contact interactions by an order of magnitude or so. In particular, for the operator $(\bar{\chi} \sigma^{\mu\nu}i\gamma_5 \chi) (\bar{q} \sigma_{\mu\nu}q)$ with DM mass $m_\chi \gtrsim 10\,\rm GeV$, the latest PandaX constraint on the DM electric dipole moment puts more stringent bounds than the previous direct detection limit.
A statistical framework in conjugation with the principle of detailed balance is employed to examine the low-energy properties i.e. charge radii and quadrupole moment of J$^P$=$\frac{1}{2}^+$ octet and J$^P$=$\frac{3}{2}^+$ decuplet baryon. The statistical approach assumes the expansion of baryonic system in terms of quark-gluon Fock states. We systematically apply operator formalism along with the statistical approach to study the charge radii and quadrupole moment of baryons. Based on the probabilities of all possible Fock states in spin, flavor and color space, the importance of sea with quarks and gluons is studied. The individual contribution of the constituent quarks and sea which contains terms of scalar, vector and tensor is explored. Due to large mass difference between strange and non-strange content, the SU(3) breaking effect are also investigated. The extent to which strange quark-antiquark pair is considered in sea is constrained by the mass of hadrons, the free energy of gluons in conformity with experimental indications. We focus on the individual contribution of strange and non-strange sea (g, $\langle u\bar u\rangle$, $\langle d\bar d\rangle$ and $\langle s\bar s\rangle$) accomodability in the respective hadrons for their charge radii and quadrupole moment. The present work has been compared with various theoretical approaches and some known experimental observations. Our computed results may provide important information for upcoming experimental findings.
The standard approaches for describing top quark production and its decay dynamics are currently mostly either based on the narrow-width (NW) limit or on off-shell fixed-order calculations. In this article we present a factorised approach for boosted top quarks that combines the properties of the NW limit and off-shell computations accounting for the dominant off-shell effects in an expansion in $m_t/Q$ with the hard scattering scale $Q$. We discuss the key ideas of our approach and show some preliminary results at tree-level.
We present an update on the study of the QCD phase transition with 3 flavors of M\"obius domain wall fermions at zero baryon density. We performed simulations on lattices of size $36^3\times12\times16$ and $24^3\times12\times32$ with a variety of quark masses at a fixed lattice spacing $a=0.1361(20)$ fm, which correspond to a temperature 121(2) MeV. By analyzing the chiral condensate, chiral susceptibilitities and Binder cumulant on $36^3\times12\times16$ lattices together with the result obtained from our previous study on $24^3\times12\times16$ lattices, we identified a crossover occurring at quark mass around $m_q^{\mathrm{\overline {MS}}}(2\, \mathrm{GeV}) \sim 3-4$ MeV for this temperature. Besides, we show the effects of residual chiral symmetry breaking on chiral condensate and chiral susceptibilities between $L_s=16$ and 32.
I present an exploration of the LHC phenomenology of the so-called top-philic ALP in the mass range between tens and hundreds of GeV. Searches through resonant production, such as ALP production in association with a $t\bar t$ pair are shown to be complementary to precision measurements of $t \bar t$ and $t\bar t t \bar t$ final states. The case where the ALP decays invisibly is also considered looking at final states with missing energy signatures.
Long-lived particles (LLPs) provide an unambiguous signal for physics beyond the Standard Model (BSM). They have a distinct detector signature, with decay lengths corresponding to lifetimes of around nanoseconds or longer. Lepton colliders allow LLP searches to be conducted in a clean environment, and such searches can reach their full physics potential when combined with machine learning (ML) techniques. In the case of LLPs searches from Higgs decay in $e^+e^-\to ZH$, we show that the LLP signal efficiency can be improved up to 99% with an LLP mass around 50 GeV and a lifetime of approximately $1$ nanosecond, using deep neural network based approaches. The signal sensitivity for the branching ratio of Higgs decaying into LLPs reaches $1.2 \times 10^{-6}$ with a statistics of $4 \times 10^{6}$ Higgs.
In this work, the transition form factors of the semileptonic decays of $B_{(s)}$ to the light scalar mesons with masses close to $1.5~\rm{GeV}$ such as $K_0^*(1430), a_0(1450)$, and $f_0(1500)$ are calculated in the framework of the light-cone sum rules (LCSR). For this purpose, the two- and three-particle $B$-meson distribution amplitudes (DA's) are used. Note that it is possible to use the $B$-meson DA's for $B_{s}$-meson in the $\rm SU(3)_F$ symmetry limit. The transition form factors are obtained in terms of the two-particle DA's up to twist-five accuracy, and the three-particle up to twist-six level. We apply two classes of the phenomenological models for the DA's of $B$-meson. The longitudinal lepton polarization asymmetries and branching fractions for the semileptonic decays of $B_{(s)}$ to the light scalar mesons are estimated with the help of these form factors.
The fully heavy axial-vector diquark-antidiquark structures $bb\overline{c} \overline{c}$ are explored by means of the QCD sum rule method. They are modeled as four-quark mesons $T_{\mathrm{1}}$ and $T_{\mathrm{2}}$ composed of $b^{T}C\sigma _{\mu \nu }\gamma _{5}b$, $\overline{c}\gamma ^{\nu }C \overline{c}^{T}$ and $b^{T}C\gamma _{\mu }\gamma _{5}b$, $\overline{c}C \overline{c}^{T}$ diquarks, respectively. The spectroscopic parameters of the tetraquarks $T_{\mathrm{1}}$ and $T_{\mathrm{2}}$ are determined in the context of the QCD two-point sum rule method. Results obtained for masses of these states $m_{1} =(12715\pm 86)~\mathrm{MeV}$ and $m_{2}=(13383\pm 92)~ \mathrm{MeV}$ are used to fix their strong decay channels. The full width $ \Gamma (T_{\mathrm{1}})$ of the diquark-antidiquark state $T_{\mathrm{1}}$ is estimated by considering the processes $T_{\mathrm{1}} \to B_{c}^{-}B_{c}^{\ast -}$ and $T_{\mathrm{1}} \to B_{c}^{\ast -}B_{c}^{\ast -} $. The decays to mesons $B_{c}^{-}B_{c}^{\ast -}$, $B_{c}^{-}(2S)B_{c}^{ \ast -}$ and $B_{c}^{\ast -}B_{c}^{\ast -}$ are employed to evaluate $\Gamma (T_{\mathrm{2}})$. Results obtained for the widths $\Gamma (T_{\mathrm{1} })=(44.3\pm 8.8)~\mathrm{MeV}$ and $\Gamma (T_{\mathrm{2}})=(82.5\pm 13.7)~ \mathrm{MeV}$ of these tetraquarks in conjunction with their masses are useful for future experimental studies of fully heavy resonances.
We present a method which relies on loop contributions from four-top SMEFT operators to single Higgs observables to contrain their Wilson coefficients. Such loop-induced terms have a non-trivial interplay with the extraction of the trilinear Higgs coupling. We show that this strategy can, for some operators, lead to more stringent bounds than direct measurement via top quark data. Finally, we mention some recent developements in the treatment of $\gamma_5$ in dimensional regularisation in the context of the SMEFT.
We consider most general effective Lagrangian up to dimension five, built with Standard Model~(SM) fields and right-handed neutrinos~(RHNs) $N_i$. Assuming that the RHNs are present near the electroweak scale, we study the phenomenology of the RHNs and highlight the differences that arise due to the inclusion of dimension five operators. We specifically focus on the production process $e^+e^-/pp\to N_i N_j$ which comes from the dimension five magnetic moment operator. We find that this production process followed by the decay chains such as $N_i\to N_j\gamma$, $N_i\to\nu_j\gamma$ and $N_i\to\ell^\pm j j$ leads to striking collider signatures which might help to probe the Majorana nature of neutrinos. We discuss the current collider constraints on this operator, as well as projected limit at future colliders. In addition, we discuss the stellar-cooling bounds applicable to the RHN mass below 0.1 GeV.
We study the large $N_\text{c}$ scaling of meson-meson scattering amplitudes in a theory with $N_\text{f}=4$ degenerate quark flavors. We focus on two different scattering channels, one having the same quantum numbers as some recently found tetraquark states at LHCb. Using L\"uscher's formalism, we study the $N_\text{c}$ dependence of the scattering phase shift and investigate the presence of exotic resonances in the scattering amplitude. We analyze the impact of including two-vector-meson and tetraquark-like operators to extract the finite-volume energies.
We present an analytic calculation of the one-loop correction to the double-real emission contribution to the zero-jettiness soft function at N3LO in QCD, accounting for both gluon-gluon and quark-antiquark soft final-state partons. We explain all the relevant steps of the computation including the reduction of phase-space integrals to master integrals in the presence of Heaviside functions, and the methods we employed to compute them.
Finite-temperature quantum field theory provides the foundation for many important phenomena in the Standard Model and extensions, including phase transitions, baryogenesis, and gravitational waves. Methods are developed to enable application of pySecDec (a Python-language-based package designed for numerical calculation of dimensionally-regulated loop integrals) to numerically evaluate finite-temperature loop integrals in the imaginary time (Matsubara) formalism. These methods consist of two main elements: an inverse Wick rotation that converts a finite-temperature loop integral into a form applicable to pySecDec, and asymptotic techniques to regulate and accelerate convergence of the Matsubara frequency summations. Numerical pySecDec evaluation of finite-temperature, two-point and three-point, one-loop topologies for scalar fields is used to illustrate and validate these new methodologies. Advantages of these finite-temperature pySecDec numerical methods are illustrated by the inclusion of multiple mass and external momentum scales.
We present the complete set of leading-color two-loop contributions required to obtain next-to-next-to-leading-order (NNLO) QCD corrections to three-jet production at hadron colliders. We obtain analytic expressions for a generating set of finite remainders, valid in the physical region for three-jet production. The analytic continuation of the known Euclidean-region results is determined from a small set of numerical evaluations of the amplitudes. We obtain analytic expressions that are suitable for phenomenological applications and we present a C++ library for their efficient and stable numerical evaluation.
The azimuthal angular decorrelation of a vector boson and jet is sensitive to QCD radiation, and can be used to probe the quark-gluon plasma in heavy-ion collisions. By using a recoil-free jet definition, the sensitivity to contamination from soft radiation on the measurement is reduced, and the complication of non-global logarithms is eliminated from our theoretical calculation. Specifically we will consider the $p_T^n$ recombination scheme, as well as the $n\to \infty$ limit, known as the winner-take-all scheme. These jet definitions also significantly simplify the calculation for a track-based measurement, which is preferred due to its superior angular resolution. We present a detailed discussion of the factorization in Soft-Collinear Effective Theory, revealing why the transverse momentum $\vec q_T$ is more complicated than the azimuthal angle. We show that potential glauber contributions do not spoil our factorization formalism, at least up to and including order $\alpha_s^3$. The resummation is carried out using the renormalization group, and all necessary ingredients are collected or calculated. We conclude with a detailed phenomenological study, finding an enhanced matching correction for high jet $p_T$ due to the electroweak collinear enhancement of a boson emission off di-jets. We also compare with the Pythia event generator, finding that our observable is very robust to hadronization and the underlying event.
We study whether the universal runaway behaviour of stringy scalar potentials towards infinite field distance limits can produce an accelerated expanding cosmology \`{a} la quintessence. We identify a loophole to some proposed bounds that forbid such asymptotic (at parametric control) accelerated expansion in 4d $\mathcal{N}=1$ supergravities, by considering several terms of the potential competing asymptotically. We then analyse concrete string theory examples coming from F-theory flux compactifications on Calabi-Yau fourfolds, extending previous results by going beyond weak string coupling to different infinite distance limits in the complex structure moduli space. We find some potential candidates to yield asymptotic accelerated expansion with a flux potential satisfying $\gamma=\frac{\|\nabla V\|}{V}<\sqrt{2}$ along its gradient flow. However, whether this truly describes an accelerated expanding cosmology remains as an open question until full moduli stabilization including the Kahler moduli is studied. Finally, we also reformulate the condition for forbidding asymptotic accelerated expansion as a convex hull de Sitter conjecture which resembles a convex hull scalar WGC for the membranes generating the flux potential. This provides a pictorial way to quickly determine the asymptotic gradient flow trajectory in multi-moduli setups and the value of $\gamma$ along it.
We present a collection of tools automating the efficient computation of large sets of theory predictions for high-energy physics. Calculating predictions for different processes often require dedicated programs. These programs, however, accept inputs and produce outputs that are usually very different from each other. The industrialization of theory predictions is achieved by a framework which harmonizes inputs (runcard, parameter settings), standardizes outputs (in the form of grids), produces reusable intermediate objects, and carefully tracks all meta data required to reproduce the computation. Parameter searches and fitting of non-perturbative objects are exemplary use cases that require a full or partial re-computation of theory predictions and will thus benefit of such a toolset. As an example application we present a study of the impact of replacing NNLO QCD K-factors in a PDF fit with the exact NNLO predictions.
It is an experimental fact that multi-particle correlations in the final states of high-energy nucleus-nucleus collisions are sensitive to collective correlations of nucleons in the wave functions of the colliding nuclei. Here, I show that this connection is more direct than it intuitively seems. With an energy deposition scheme inspired by high-energy quantum chromodynamics, and within a linearized description of initial-state fluctuations in the quark-gluon plasma, I exhibit relations between $N$-particle correlations in the final states of nuclear collisions and $N$-nucleon density distributions in the colliding nuclei. This result formally justifies the sensitivity of the outcome of high-energy collisions to features such as nuclear deformations. It paves the way, thus, to systematic studies of the impact of state-of-the-art nuclear interactions in such processes.
This paper presents a comparative analysis of three distinct methods used to calculate the collisional energy loss of heavy quarks in Quark-Gluon Plasma. The study focuses on the calculation of the nuclear suppression factor of charm quarks in Pb-Pb collisions at $\sqrt{S_{NN}} = 5.02$ TeV. All three models are examined using the same numerical evolution based on the well-known Fokker-Planck equation by considering critical phenomena like a non-equilibrium state at the onset of heavy ion collision. The outcomes of each approach are compared with the latest data from ALICE and ATLAS experiments spanning from 2018 to 2022. This study aims to compare the degree of agreement between each approach and recently obtained experimental data, in the intermediate and high $P_T$ regions.
We investigate a baryon and its dilatation modes in holographic QCD based on the Sakai-Sugimoto model, which is expressed as a 1+4 dimensional U($N_f$) gauge theory in the flavor space. For spatially rotational symmetric systems, we apply a generalized version of the Witten Ansatz, and reduce 1+4 dimensional holographic QCD into a 1+2 dimensional Abelian Higgs theory in a curved space. In the reduced theory, the holographic baryon is described as a two-dimensional topological object of an Abrikosov vortex. We numerically calculate the baryon solution of holographic QCD using a fine and large lattice with spacing of 0.04 fm and size of 10 fm. Using the relation between the baryon size and the zero-point location of the Higgs field in the description with the Witten Ansatz, we investigate a various-size baryon through this vortex description. As time-dependent size-oscillation modes (dilatation modes) of a baryon, we numerically obtain the lowest excitation energy of 577 MeV and deduce the dilatational excitation of a nucleon to be the Roper resonance N$^*$(1440).
We study the possibly-existing molecular pentaquark states with open charm and bottom flavors, {\it i.e.}, the states with the quark contents $c\bar{b}qqq$ and $b\bar{c}qqq$ ($q=u,d,s$). We investigate the meson-baryon interactions through the coupled-channel unitary approach within the local hidden-gauge formalism, and extract the poles by solving the Bethe-Salpeter equation in coupled channels. These poles qualify as molecular pentaquark states, which are dynamically generated from the meson-baryon interactions through the exchange of vector mesons. Our results suggest the existence of the $\Sigma_c^{(*)} B^{(*)}$ and $\Sigma_b^{(*)} \bar{D}^{(*)}$ molecular states with isospin $I=1/2$, the $\Xi_c^{(\prime,*)} B^{(*)}$ and $\Xi_b^{(\prime,*)} \bar{D}^{(*)}$ molecular states with isospin $I=0$ and $I=1$, as well as the $\Omega_c^{(*)} B^{(*)}$ and $\Omega_b^{(*)} \bar D^{(*)}$ molecular states with isospin $I=1/2$.
We embark on a systematical analysis of the quark and gluon gravitational form factors (GFFs) of the proton, by connecting energy-momentum tensor (EMT) and the near-threshold vector meson photoproduction (NTVMP). Concretely, the quark contributions of GFFs are determined by global fitting the cross section of the lightest vector meson $\rho^0$ photoproduction. Combined with the gluon GFFs achieved from heavy quarkonium $J/\psi$ photoproduction data, the complete GFFs are obtained and compared with the experimental results and Lattice QCD determinations. In addition, we use the Resonances Via Pad\'{e} (RVP) method based on the Schlessinger Point Method (SPM) to obtain a model-independent quark $D$-term distribution by direct analytical continuation of Deep Virtual Compton Scattering (DVCS) experimental data. If errors are considered, the results obtained by RVP are basically consistent with those obtained by NTVMP. Moreover, the comprehensive information on GFFs helps us to uncover the mass distribution and mechanical properties inside the proton. This work is not only an important basis for delving the proton enigmatic properties, unraveling the secrets of the proton internal nature but also have significance theoretical guiding for future JLab and EICs experimental measurements.
The scale evolution of parton distributions is determined by universal splitting functions. As a milestone towards the computation of these functions to four-loop order in QCD, we compute all contributions to the pure-singlet quark-quark splitting functions that involve two closed fermion loops. The splitting functions are extracted from the pole terms of off-shell operator matrix elements, and the workflow for their calculation is outlined. We reproduce known results for the non-singlet four-loop splitting functions and validate our new pure-singlet results against fixed Mellin moments.
The FASER{\nu} experiment has detected the first neutrino events coming from LHC. Near future high-statistic neutrino samples will allow us to search for new physics within the neutrino sector. Motivated by the forthcoming promising FASER{\nu} neutrino data, and its succesor, FASER{\nu}2, we study its potential for testing the unitarity of the neutrino lepton mixing matrix. Although it would be challenging for FASER{\nu} and FASER{\nu}2 to have strong constraints on this kind of new physics, we discuss its role in contributing to a future improved global analysis.
There is a major mismatch between the charged pion yields in Au+Au collisions at low energies calculated by various transport models and the experimental measured values from the Hades collaboration. In this work, reasonable improvements on the equation of state, in-medium modification of cross sections, and the influence of the nuclear potential for Delta resonances will be investigated in the framework of the GiBUU transport model. As a result, we demonstrate that theoretical calculations can indeed describe the charged pion yields measured by Hades for Au+Au collisions rather well, but that a mismatch then remains between calculations and data for the yields of neutral pions extracted from dileptons within the same experiment.
Recently, Belle II reported the observation of the decay $B\to K M_X$, $M_X$ the missing mass, with the branching ratio much exceeding ${\cal B}(B\to K \nu\bar\nu)$ which is the only Standard Model (SM) process contributing to this reaction. If confirmed, this might be an indication of new nonSM particles produced in this decay. One of the possible explanations of the observed effect could be light dark-matter (DM) particles produced via a scalar mediator field. We give simple arguments, that a combined analysis of the $B\to K M_X$ and $B\to K^* M_X$ reactions would be a clean probe of the scalar mediator scenario: (i) making use of an observed value ${\cal B}(B\to K M_X)\simeq 5.4\, {\cal B}(B\to K \nu\bar\nu)_{\rm SM}$ and (ii) assuming that the effect is due to the light dark matter coupling to the top quark via a {\it scalar} mediator field, one finds an upper limit ${\cal B}(B\to K^* M_X) < 2.8 \, {\cal B}(B\to K^* \nu\bar\nu)_{\rm SM}$. Within the discussed scenario, this upper limit does not depend on the mass of the scalar mediator nor on the specific details of the unobserved dark-matter particles in the final state.
We report a new result for the $N_f \,C_F^3$ contribution to the four-loop anomalous dimensions of non-singlet, twist-two operators in Quantum Chromodynamics. This result is obtained through computations of off-shell operator matrix elements. Employing integration-by-parts reductions and differential equations with respect to a tracing parameter allowed us to derive analytic results valid for arbitrary Mellin moment $n$.
We consider the Type-II seesaw model extended with another Higgs doublet, which is odd under the $Z_2$ symmetry. We look for the possibility of triggering the electroweak symmetry breaking via radiative effects. The Higgs mass parameter changes sign from being positive at higher energy scales to negative at lower energy scales in the presence of the TeV scalar triplet. The Planck scale perturbativity is demanded and the electroweak phase transition is studied using two-loop $\beta$-functions. The maximum allowed values for the interaction quartic coupling of the second doublet field and the triplet field with the Higgs field are $\lambda_3=0.15$ and $\lambda_{\Phi_{1\Delta}}=0.50$, respectively. Considering these EW values, the first-order phase transition, i.e., $\phi_{+}(T_c)/T_c\sim 0.6$ is satisfied only for vanishing doublet and triplet bare mass parameters, $m_{\Phi_2}=0.0$ GeV and $m_{\Delta}=0.0$ GeV. The small non-zero induced vacuum expectation value for the scalar triplet also generates the neutrino mass, and the lightest stable neutral particle from the inert doublet satisfies the dark matter constraints for the chosen parameter space. The impact of the thermal corrections on the stability of the electroweak vacuum is also studied, and the current experimental values of the Higgs mass and the top mass lie in the stable region both at the zero temperature and the finite temperature.
We explain the microscopic origin of linear confinement potential with the Casimir scaling in generic confining gauge theories. In the low-temperature regime of confining gauge theories such as QCD, Polyakov lines are slowly varying Haar random modulo exponentially small corrections with respect to the inverse temperature, as shown by one of the authors (M.~H.) and Watanabe. With exact Haar randomness, computation of the two-point correlator of Polyakov loops reduces to the problem of random walk on group manifold. Linear confinement potential with approximate Casimir scaling except at short distances follows naturally from slowly varying Haar randomness. With exponentially small corrections to Haar randomness, string breaking and loss of Casimir scaling at long distance follow. Hence we obtain the Casimir scaling which is only approximate and holds only at intermediate distance, which is precisely needed to explain the results of lattice simulations. For $(1+1)$-dimensional theories, there is a simplification that admits the Casimir scaling at short distances as well.
With the increasing usage of machine-learning in high-energy physics analyses, the publication of the trained models in a reusable form has become a crucial question for analysis preservation and reuse. The complexity of these models creates practical issues for both reporting them accurately and for ensuring the stability of their behaviours in different environments and over extended timescales. In this note we discuss the current state of affairs, highlighting specific practical issues and focusing on the most promising technical and strategic approaches to ensure trustworthy analysis-preservation. This material originated from discussions in the LHC Reinterpretation Forum and the 2023 PhysTeV workshop at Les Houches.
A strong enhancement of deuteron production in jets has been recently observed in proton-proton collisions at LHC. We show that the effect is due to two independent factors: a collimation of jet nucleons and a smallness of nucleon source. The coalescence parameter of jet deuterons is shown to acquire its maximal possible value.
In this review, the seesaw mechanism for generating the mass of active light neutrinos (both Majorana and Dirac) is considered on the basis of effective field theory. In particular, we review certain models that extend the Standard Model by introducing heavy sterile neutrinos and discuss the corresponding mechanisms for generating small masses of active neutrinos. Two Appendices briefly describe the properties of Weyl, Dirac, and Majorana spinors in four dimensions and the interrelations between such spinors. The third Appendix provides a simple proof of the theorem on Takagi diagonalization of a mass matrix for Majorana fermions.
We consider Majorana lattices with two-site interactions consisting of a general function of the fermion bilinear. The models are exactly solvable in the limit of a large number of on-site fermions. The four-site chain exhibits a quantum phase transition controlled by the hopping parameters and manifests itself in a discontinuous entanglement entropy, obtained by constraining the one-sided modular Hamiltonian. Inspired by recent work within the AdS/CFT correspondence, we identify transitions between types of von Neumann operator algebras throughout the phase diagram. We find transitions of the form II$_1\leftrightarrow\,$III$\,\,\leftrightarrow\,\,$I$_\infty$ that reduce to II$_1\leftrightarrow\,\,$I$_\infty$ in the strongly interacting limit, where they connect non-factorized and factorized ground states. Our results provide novel realizations of such transitions in a controlled many-body model.
We make lattice generalization of two well-known zero dimensional models of quantum spin glass, Sachdev-Ye (SY) and spherical quantum $p$-spin glass model, to one dimension for studying crossovers in non-local scrambling dynamics due to glass transition, complex dynamics, and quantum and thermal fluctuations in paramagnetic (PM) and spin glass (SG) phases. In the SY chain of quantum dots, each described by infinite-range random Heisenberg model of $N$ spin-$S$ $SU(M)$ spins, we obtain the quantum Lyapunov exponent $\lambda_\mathrm{L}$ and butterfly velocity $v_B$ as a function of temperature $T$ and the quantum parameter $S$ across the PM-SG phase boundary using a bosonic spinon representation in the large-$N,M$ limit. In particular, we extract asymptotic $T$ and $S$ dependence, e.g., power laws, for $\lambda_\mathrm{L}$ and $v_B$ in different regions deep inside the phases and near the replica symmetry breaking SG transition. We find the chaos to be non-maximal almost over the entire phase diagram. Very similar results for chaos indicators are found for the $p$-spin glass chain as a function of temperature and a suitable quantum parameter $\Gamma$, with some important qualitative differences. In particular, $\lambda_\mathrm{L}$ and $v_B$ exhibit a maximum, coinciding with onset of complex glassy relaxation, above the glass transition as a function of $T$ and $\Gamma$ in the PM phase of the $p$-spin glass model. In contrast, the maximum is only observed as a function of $S$, but not with temperature, in the PM phase of SY model. The maximum originates from enhanced chaos due to maximal complexity in the glassy landscape. Thus, the results in the SY model indicate very different evolution of glassy complexity with quantum and thermal fluctuations.
We analyze the phases of theories which only have a microscopic $\mathbb{Z}_N$ 1-form symmetry, starting with a topological BF theory and deforming it in accordance with microscopic symmetry. These theories have a well-defined notion of confinement. Prototypical examples are pure $SU(N)$ gauge theories and $\mathbb{Z}_N$ lattice gauge theories. Our analysis shows that in spacetime dimensions $d=2$ only the confined phase is generically possible. In $d=3,4$ the confined phase and a topological BF phase are both generic, while in $d=4$ a phase with a massless photon is also possible. We construct a $\mathbb{Z}_N$ lattice gauge theory with a deformation which, surprisingly, produces up to $(N-1)$ photons. We give an interpretation of these findings in terms of two competing pictures of confinement -- proliferation of monopoles and proliferation of center vortices -- and conclude that the proliferation of center vortices is a necessary but not sufficient condition for confinement, while that of monopoles is both necessary and sufficient.
We construct the most general four-dimensional ${\cal N}=4$ supergravity coupled to an arbitrary number $n$ of vector multiplets in which the global scaling symmetry is gauged, in addition to a subgroup of $\text{SL}(2,\mathbb{R}) \times \text{SO}(6,n)$. The various gaugings are parametrized by an embedding tensor built out of $2 \binom{n+6}{3}+4(n+6)$ parameters that satisfy a specific set of quadratic consistency constraints, to which we provide an explicit solution. We also derive the local supersymmetry transformation rules and the equations of motion for the four-dimensional ${\cal N}=4$ matter-coupled supergravity with local scaling symmetry. Such supergravity theories do not possess an action, since the scaling symmetry is only an on-shell symmetry of the corresponding ungauged theories.
We recently described a protocol for computing the potential energy in heterotic M-theory for the dilaton, complex structure and K\"ahler moduli. This included the leading order non-perturbative contributions to the complex structure, gaugino condensation and worldsheet instantons assuming a hidden sector that contains an anomalous U(1) structure group embedded in $E_8$. In this paper, we elucidate, in detail, the mathematical and computational methods required to utilize this protocol. These methods are then applied to a realistic heterotic M-theory model, the $B-L$ MSSM, whose observable sector is consistent with all particle physics requirements. Within this context, it is shown that the dilaton and universal moduli can be completely stabilized at values compatible with every phenomenological and mathematical constraint -- as well as with $\Lambda$CDM cosmology. We also show that the heterotic M-theory vacua are consistent with all well-supported Swampland conjectures based on considerations of string theory and quantum gravity, and we discuss the implications of dark energy theorems for compactified theories.
In the standard von Neumann interaction used in Quantum measurements, the chosen observable to which the environment (apparatus) entangles is exactly reproduced in the state of the environment, thereby decohering the quantum system in the eigenbasis of the observable. We relax this by allowing for imperfect measurements whereby the environment evolves to a state that approximately, but not exactly, reflects the state of the system. In this scheme it is possible to attain approximate decoherence of conjugate quantities that resembles classical physics, which we demonstrate using an example.
One of the simplest examples of non-invertible symmetries in higher dimensions appears in 4d Maxwell theory, where its $SL(2,\mathbb{Z})$ duality group can be combined with gauging subgroups of its electric and magnetic 1-form symmetries to yield such defects at many different values of the coupling. Even though $\mathcal{N}=4$ Super-Yang-Mills (SYM) theory also has an $SL(2,\mathbb{Z})$ duality group, it only seems to share two types of such non-invertible defects with Maxwell theory (known as duality and triality defects). Motivated by this apparent difference, we begin our investigation of the fate of these symmetries by studying the case of 4d $\mathcal{N}=4$ $U(1)$ gauge theory which contains Maxwell theory in its content. Surprisingly, we find that the non-invertible defects of Maxwell theory give rise, when combined with the standard $U(1)$ symmetry acting on the free fermions, to defects which act on local operators as elements of the $U(1)$ outer-automorphism of the $\mathcal{N}=4$ superconformal algebra, an operation that was referred to in the past as the "bonus symmetry". Turning to the nonabelian case of $\mathcal{N}=4$ SYM, the bonus symmetry is not an exact symmetry of the theory but is known to emerge at the supergravity limit. Based on this observation we study this limit and show that if it is taken in a certain way, non-invertible defects that realize different elements of the bonus symmetry emerge as approximate symmetries, in analogy to the abelian case.
We provide a first principle definition of cosmological correlation functions for a large class of scalar toy models in arbitrary FRW cosmologies, in terms of novel geometries we name {\it weighted cosmological polytopes}. Each of these geometries encodes a universal rational integrand associated to a given Feynman graph. In this picture, all the possible ways of organising, and computing, cosmological correlators correspond to triangulations and subdivisions of the geometry, containing the in-in representation, the one in terms of wavefunction coefficients and many others. We also provide two novel contour integral representations, one connecting higher and lower loop correlators and the other one expressing any of them in terms of a building block. We study the boundary structure of these geometries allowing us to prove factorisation properties and Steinmann-like relations when single and sequential discontinuities are approached. We also show that correlators must satisfy novel vanishing conditions. As the weighted cosmological polytopes can be obtained as an orientation-changing operation onto a certain subdivision of the cosmological polytopes encoding the wavefunction of the universe, this picture allows us to sharpen how the properties of cosmological correlators are inherited from the ones of the wavefunction. From a mathematical perspective, we also provide an in-depth characterisation of their adjoint surface.
In the present paper we study some new classical Lorentz violating effects in planar electrodynamics due to the presence of stationary point-like field sources. Starting from the Carroll-Field-Jackiw model defined in (3+1) dimensions, which belongs to the electromagnetic CPT-odd sector of the Standard Model Extension (SME), we apply the dimensional reduction procedure obtaining a (2+1)-dimensional model that encompasses an electromagnetic sector composed of the Maxwell-Chern-Simons electrodynamics, a pure scalar sector described by a massless Klein-Gordon field, and a mixed sector where the background vector mediates contributions involving both the scalar and the gauge fields. For all the sectors of this planar theory, we explore some physical phenomena that arise from the interactions between external sources. Specifically, we obtain perturbative effects up to second order in the background vector related to the presence of both electric and scalar planar charges and Dirac points.
This is an invited survey article on higher gauge theory for the Encyclopedia of Mathematical Physics, 2nd edition. In particular, we provide a lightning introduction to higher structures and to the construction of the kinematical data of higher gauge theories, i.e. connections on higher principal bundles. We also summarise the most important applications and dynamical principles that have appeared in the literature, and we close with comments on related areas.
In this paper, we fix the complex structure and explore the moduli space of the heterotic system by considering two different yet "dual" deformation paths starting from a K\"ahler solution. They correspond to deformation along the Bott-Chern cohomology class and the Aeppli cohomology class respectively. Using the implicit function theorem, we prove the local existence of heterotic solutions along these two paths and hence establish an initial step to construct local moduli coordinates around a K\"ahler solution.
Given any half-sided modular inclusion of standard subspaces, we show that the entropy function associated with the decreasing one-parameter family of translated standard subspaces is convex for any given (not necessarily smooth) vector in the underlying Hilbert space. In second quantisation, this infers the convexity of the vacuum relative entropy with respect to the translation parameter of the modular tunnel of von Neumann algebras. This result allows us to study the QNEC inequality for coherent states in a free Quantum Field Theory on a stationary curved spacetime, given a KMS state. To this end, we define wedge regions and appropriate (deformed) subregions. Examples are given by the Schwarzschild spacetime and null translated subregions with respect to the time translation Killing flow. More generally, we define wedge and stripe regions on a globally hyperbolic spacetime, so to have non trivial modular inclusions of von Neumann algebras, and make our analysis in this context.
We consider the $U(1)$ gauge theory on a four-dimensional torus, where the instanton number is restricted to an integral multiple of $p$. This theory possesses the nontrivial higher-group structure, which can be regarded as a generalization of the Green--Schwarz mechanism, between $\mathbb{Z}_q$ $1$-form and $\mathbb{Z}_{pq}$ $3$-form symmetries. Here, $\mathbb{Z}_q$ is a subgroup of the center of~$U(1)$. Following the recent study of the lattice construction of the $U(1)/\mathbb{Z}_q$ principal bundle, we examine how such a structure is realized on the basis of lattice regularization.
We study four-point functions of arbitrary half-BPS operators in a 4-dimensional $\mathcal{N}=2$ SCFT with flavour group $SO(8)$ at genus-zero and strong 't Hooft coupling, corresponding - via AdS/CFT - to the ($\alpha'$ expansion of the) Veneziano amplitude on an AdS$_5 \times$S$^3$ background. We adapt a procedure first proposed by Abl, Heslop and Lipstein in the context of AdS$_5 \times$S$^5$, and postulate the existence of an effective action in terms of an $8$-dimensional scalar field valued in the adjoint of the flavour group. The various Kaluza-Klein correlators can then be computed by uplifting the standard AdS/CFT prescription to the full product geometry with AdS bulk-to-boundary propagators and Witten diagrams replaced by suitable AdS$_5 \times$S$^3$ versions. After elucidating the main features of the procedure, valid at all orders in $\alpha'$, we show explicit results up to order $\alpha'^{5}$. The results provide further evidence of a novel relation between AdS$\times$S and flat amplitudes - which made its first appearance in $\mathcal{N}=4$ SYM - that is perhaps the most natural extension of the well known flat-space limit proposed by Penedones to cases where AdS and S have the same radius.
We construct non-commutative theories with the Moyal-Weyl product in the Double Field Theory (DFT) framework. We deform the infinitesimal generalized diffeomorphisms and the Leibniz rule in a consistent way. The prescription requires a generalized star metric, which can be thought of as the fundamental double metric, in order to construct the action. Finally we use the generalized scalar field dynamics and the generalized scalar field-perfect fluid correspondence to construct the generalized energy momentum-tensor of a perfect fluid in the non-commutative double geometry. The present formalism paves the way to the study of string cosmologies scenarios including the Moyal-Weyl product in a T-duality invariant way.
We develop a new method for finding the quantum probability density of arrival at the detector. The evolution of the quantum state restricted to the region outside of the detector is described by a restricted Hamiltonian that contains a non-hermitian boundary term. The non-hermitian term is shown to be proportional to the flux of the probability current operator through the boundary, which implies that the arrival probability density is equal to the flux of the probability current.
This paper proves quantum modularity of both functions from $\mathbb{Q}$ and $q$-series associated to the closed manifold obtained by $-1/2$ surgery on the figure-eight knot, $4_1(-1,2)$. In a sense, this is a companion to work of Garoufalidis-Zagier where similar statements were studied in detail for some simple knots. It is shown that quantum modularity for closed manifolds provides a unification of Chen-Yang's volume conjecture with Witten's asymptotic expansion conjecture. Additionally we show that $4_1(-1,2)$ is a counter-example to previous conjectures relating the Witten-Reshetikhin-Turaev invariant and the $\widehat{Z}(q)$ series. This could be reformulated in terms of a "strange identity", which gives a volume conjecture for the $\widehat{Z}$ invariant. Using factorisation of state integrals, we give conjectural but precise $q$-hypergeometric formulae for generating series of Stokes constants of this manifold. We find that the generating series of Stokes constants is related to the 3d index of Dimofte-Gaiotto-Gukov of $4_1(-1,2)$ proposed by Gang-Yonekura. This extends the equivalent conjecture of Garoufalidis-Gu-Mari\~no for knots to closed manifolds. This work appeared in a similar form in the author's thesis.
This is a review article on the quantum toroidal algebras, focusing on their roles in various solvable structures of 2d conformal field theory, supersymmetric gauge theory, and string theory. Using $\mathcal{W}$-algebras as our starting point, we elucidate the interconnection of affine Yangians, quantum toroidal algebras, and double affine Hecke algebras. Our exploration delves into the representation theory of the quantum toroidal algebra of $\mathfrak{gl}_1$ in full detail, highlighting its connections to partitions, $\mathcal{W}$-algebras, Macdonald functions, and the notion of intertwiners. Further, we also discuss integrable models constructed on Fock spaces and associated $\mathcal{R}$-matrices, both for the affine Yangian and the quantum toroidal algebra of $\mathfrak{gl}_1$. The article then demonstrates how quantum toroidal algebras serve as a unifying algebraic framework that bridges different areas in physics. Notably, we cover topological string theory and supersymmetric gauge theories with eight supercharges, incorporating the AGT duality. Drawing upon the representation theory of the quantum toroidal algebra of $\mathfrak{gl}_1$, we provide a rather detailed review of its role in the algebraic formulations of topological vertex and $qq$-characters. Additionally, we briefly touch upon the corner vertex operator algebras and quiver quantum toroidal algebras.
Infrared (IR) dimension function $d_\text{IR}(\lambda)$ characterizes the space effectively utilized by QCD quarks at Dirac scale $\lambda$, and indirectly the space occupied by glue fields. It was proposed that its non-analytic behavior in thermal infrared phase reflects the separation of QCD system into an IR component and an independent bulk. Here we study the ``plateau modes" in IR component, whose dimensional properties were puzzling. Indeeed, in the recent metal-to-critical scenario of transition to IR phase, this low-dimensional plateau connects the Anderson-like mobility edge $\lambda_\text{IR}=0$ in Dirac spectrum with mobility edges $\pm \lambda_\text{A}$. For this structure to be truly Anderson-like, plateau modes have to be exponentially localized, implying that both the effective distances $L_\text{eff} \propto L^\gamma$ and the effective volumes $V_\text{eff} \propto L^{d_\text{IR}}$ in these modes grow slower than any positive power of IR cutoff $L$. Although $\gamma=0$ was confirmed in the plateau, it was found that $d_\text{IR}\approx 1$. Here we apply the recently proposed multidimension technique to the problem. We conclude that a plateau mode of pure-glue QCD at UV cutoff $a \!=\! 0.085\,$fm occupies a subvolume of IR dimension zero with probability at least 0.9999, substantiating this aspect of metal-to-critical scenario to a respective degree.
We construct all possible complete intersection Calabi-Yau five-folds in a product of four or less complex projective spaces, with up to four constraints. We obtain $27068$ spaces, which are not related by permutations of rows and columns of the configuration matrix, and determine the Euler number for all of them. Excluding the $3909$ product manifolds among those, we calculate the cohomological data for $12433$ cases, i.e. $53.7 \%$ of the non-product spaces, obtaining $2375$ different Hodge diamonds. The dataset containing all the above information is available at https://www.dropbox.com/scl/fo/z7ii5idt6qxu36e0b8azq/h?rlkey=0qfhx3tykytduobpld510gsfy&dl=0 . The distributions of the invariants are presented, and a comparison with the lower-dimensional analogues is discussed. Supervised machine learning is performed on the cohomological data, via classifier and regressor (both fully connected and convolutional) neural networks. We find that $h^{1,1}$ can be learnt very efficiently, with very high $R^2$ score and an accuracy of $96\%$, i.e. $96 \%$ of the predictions exactly match the correct values. For $h^{1,4},h^{2,3}, \eta$, we also find very high $R^2$ scores, but the accuracy is lower, due to the large ranges of possible values.
Analyzing the representations of the Lorentz group, we give a systematic count and construction of all the possible Lagrangians describing an antisymmetric rank two tensor field. The count yields two scalars: the gauge invariant Kalb-Ramond model, equivalent to the sigma model and familiar from super gravity and string theory, and the conformally invariant Avdeev-Chizhov model, which describes self-dual tensors. The count also includes a third invariant, a pseudoscalar, which is an antisymmetrized form of the Avdeev-Chizhov Lagrangian, first noticed in the $SU(2/1)$ superalgebraic model of the weak interactions. This model is also conformally invariant, and naturally implements the Landau $CP$ symmetry. Then, by extending the Duffin-Kemmer-Petiau 10 component formalism, we recover the model Lagrangians as first order systems. To complete the analysis we classify all local Lorentz invariant potentials (mass terms and quartic couplings) for charged antisymmetric tensor fields coupled to a Yang-Mills field.
We compute the potential energy for the dilaton, complex structure and Kahler moduli and search of realistic vacua of heterotic M-theory compactified on Calabi-Yau threefolds. We present a protocol for deriving the potential that combines the non-perturbative complex structure, gaugino condensate and worldsheet instanton superpotentials in theories in which the hidden sector contains an anomalous $U(1)$ structure group. The Green-Schwarz anomaly cancellation induces inhomogeneous axion transformations for the imaginary components of the dilaton and Kahler modulus. Using this protocol we obtain explicit examples in which potential has a global minimum at negative or zero vacuum density or a metastable minimum with positive vacuum density. In all three cases, the dilaton, Kahler modulus and associated axion moduli are completely stabilized. Finally, we show that, for any of these vacua, the potential energy satisfies the large scalar field Swampland conjecture.
We formalize the computation of tree-level scattering amplitudes in terms of the homotopy transfer of homotopy algebras, illustrating it with scalar $\phi^3$ and Yang-Mills theory. The data of a (gauge) field theory with an action is encoded in a cyclic homotopy Lie or $L_{\infty}$ algebra defined on a chain complex including a space of fields. This $L_{\infty}$ structure can be transported, by means of homotopy transfer, to a smaller space that, in the massless case, consists of harmonic fields. The required homotopy maps are well-defined since we work with the space of finite sums of plane-wave solutions. The resulting $L_{\infty}$ brackets encode the tree-level scattering amplitudes and satisfy generalized Jacobi identities that imply the Ward identities. We further present a method to compute color-ordered scattering amplitudes for Yang-Mills theory, using that its $L_{\infty}$ algebra is the tensor product of the color Lie algebra with a homotopy commutative associative or $C_{\infty}$ algebra. The color-ordered scattering amplitudes are then obtained by homotopy transfer of $C_{\infty}$ algebras.
Recent experiments strongly indicate deep connections between transports of strange metal and high $T_c$ superconductors. For example, the dependence of the zero-temperature phase stiffness on the critical superconducting temperature is generally linear, which is incompatible with the standard Bardeen-Cooper-Schrieffer description. We explore the scaling relations among superconducting critical temperature, superfluid density, and momentum dissipation (disorder) strength for the Gubser-Rocha model with extensions in the probe limit. The critical temperature is evaluated by using both the Sturm-Liouville eigenvalue method and numerical calculations. In the normal phase, we show that the critical temperature is proportional to the momentum dissipation (disorder) strength in a certain parameter range. In the superconducting phase, studying the AC conductivity analytically and numerically, we find linear dependence of zero-temperature superfluid density (phase stiffness) on the critical superconducting temperature, which is consistent with recent experiments of high $T_c$ superconductors. These results further underpin the deep connections between strange metal and high $T_c$ superconductors.
We numerically address the issue of which monopole operators are relevant under renormalization group flow in three-dimensional parity-invariant noncompact QED with $4$ flavors of massless two-component Dirac fermion. Using lattice simulation and finite-size scaling analysis of the free energy to introduce monopole-antimonopole pairs in $N=4$ and $N=12$ flavor noncompact QED$_3$, we estimate the infrared scaling dimensions of monopole operators that introduce $2\pi$ and $4\pi$ fluxes around them. We first show that the estimates for the monopole scaling dimensions are consistent with the large-$N$ expectations for $N=12$ QED$_3$. Applying the same procedure in $N=4$ QED$_3$, we estimate the scaling dimension of $4\pi$ flux monopole operator to be $3.7(3)$, which allows the possibility of the operator being irrelevant. This finding offers support to the scenario in which higher-flux monopoles are irrelevant deformations to the Dirac spin liquid phase that could be realized on certain non-bipartite lattices by forbidding $2\pi$-flux monopoles.
A search for a new heavy boson produced via gluon-fusion in the four-lepton channel with missing transverse momentum or jets is performed. The search uses proton-proton collision data equivalent to an integrated luminosity of 139 fb$^{-1}$ at a centre-of-mass energy of 13 TeV collected by the ATLAS detector between 2015 and 2018 at the Large Hadron Collider. This study explores the decays of heavy bosons: $R\rightarrow SH$ and $A\rightarrow ZH$, where $R$ is a CP-even boson, $A$ is a CP-odd boson, $H$ is a CP-even boson, and $S$ is considered to decay into invisible particles that are candidates for dark matter. In these processes, $S\rightarrow \textrm{invisible}$ and $H\rightarrow ZZ$. The $Z$ boson associated with the heavy scalar boson $H$ decays into all decay channels of the $Z$ boson. The mass range under consideration is 390-1300 (320-1300) GeV for the $R$ ($A$) boson and 220-1000 GeV for the $H$ boson. No significant deviation from the Standard Model backgrounds is observed. The results are interpreted as upper limits at a 95% confidence level on the cross-section times the branching ratio of the heavy resonances.
We report the results of the first search for $B^-$ decays to the $\bar{\Xi}_{c}^{0} \bar{\Lambda}_{c}^{-}$ final state using 711~${\rm fb^{-1}}$ of data collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The results are interpreted in terms of both direct baryon-number-violating $B^-$ decay and $\Xi_{c}^{0}-\bar{\Xi}_{c}^{0}$ oscillations which follow the Standard Model decay $B^- \to \Xi_{c}^{0} \bar{\Lambda}_{c}^{-}$. We observe no evidence for baryon number violation and set the 95\% confidence-level upper limits on the ratio of baryon-number-violating and Standard Model branching fractions ${\mathcal{B}(B^- \rightarrow \bar{\Xi}_{c}^{0} \bar{\Lambda}_{c}^{-})}/{\mathcal{B}(B^- \rightarrow \Xi_{c}^{0} \bar{\Lambda}_{c}^{-})}$ to be $< 2.7\%$ and on the $\Xi_{c}^{0} - \bar{\Xi}_{c}^{0}$ oscillation angular frequency $\omega$ to be $< 0.76\ \mathrm{ps}^{-1}$ (equivalent to $\tau_{\rm mix} > 1.3$~ps).
The top quark mass measurements are based either on a direct kinematic reconstruction of the top quark decay products or on indirect measurements, where an observable sensitive to the top quark mass, such as the production cross section, is used to infer it. The ATLAS and CMS collaborations have measured the top quark mass using various methods with increasing precision. Recent measurements using 13 TeV pp collision data recorded at the LHC are presented in this review.
Heavy-ion collisions undergo various stages in their evolution and it is crucial to disentangle the initial- and final-stage effects. In this work, we report measurements of two types of observables: (i) charge-dependent directed flow ($\Delta v_1$), which is sensitive to the initial ultra-strong electromagnetic fields, and (ii) flow correlations, such as $r_n (\eta)$ which is sensitive to the initial longitudinal de-correlation, and correlations among flow harmonics. These measurements contribute to constraining the initial state of the collisions, and through a comprehensive beam energy scan, we gain significant insights into the system evolution in the presence of initial spatial asymmetry and electromagnetic fields.
Measurements of inclusive and differential production cross-sections of a top-quark-top-antiquark pair in association with a $W$ boson ($t\bar{t}W$) are presented. They are performed by targeting final states with two same-sign or three isolated leptons (electrons or muons) and are based on $\sqrt{s}=13$ TeV proton-proton collision data with an integrated luminosity of 140 fb$^{-1}$, recorded from 2015 to 2018 with the ATLAS detector at the Large Hadron Collider. The inclusive $t\bar{t}W$ production cross-section is measured to be $880 \pm 80$ fb, compared to a reference theoretical prediction of $745 \pm 50\,\textrm{(scale)} \pm 13\,\textrm{(2-loop approx.)} \pm 19\,\textrm{(PDF,} \alpha_{\textrm{S}})$ fb. Differential cross-section measurements characterise this process in detail for the first time. Several particle-level observables are compared with a variety of theoretical predictions, which generally agree well with the normalised differential cross-section results. Additionally, the relative charge asymmetry of $t\bar{t}W^{+}$ and $t\bar{t}W^{-}$ is measured inclusively to be ${A_{\mathrm{C}}^{\mathrm{rel}}} = 0.33 \pm 0.05$, in very good agreement with the theoretical prediction of $0.322 \pm 0.003\,\mathrm{(scale)} \pm 0.007\,\mathrm{(PDF)}$, as well as differentially.
A search for resonances in events with the $\gamma$+jet final state has been performed using proton-proton collision data collected at $\sqrt{s}$ = 13 TeV by the CMS experiment at the LHC. The total data analyzed correspond to an integrated luminosity of 138 fb$^{-1}$. Models of excited quarks and quantum black holes are considered. Using a wide-jet reconstruction for the candidate jet, the $\gamma$+jet invariant mass spectrum measured in data is examined for the presence of resonances over the standard model continuum background. The background is estimated by fitting the mass distribution with a functional form. The data exhibit no statistically significant deviations from the expected standard model background. Exclusion limits at 95% confidence level on the resonance mass and other parameters are set. Excited light-flavor quarks (excited bottom quarks) are excluded up to a mass of 6.0 (3.8) TeV. Quantum black hole production is excluded for masses up to 7.5 (5.2) TeV in the Arkani-Hamed-Dimopoulos-Dvali (Randall-Sundrum) model. These lower mass bounds are the most stringent to date among those obtained in the $\gamma$+jet final state.
New particles with large masses that decay into hadronically interacting particles are predicted by many models of physics beyond the Standard Model. A search for a massive resonance that decays into pairs of dijet resonances is performed using 140 fb$^{-1}$ of proton$-$proton collisions at $\sqrt{s}=13$ TeV recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Resonances are searched for in the invariant mass of the tetrajet system, and in the average invariant mass of the pair of dijet systems. A data-driven background estimate is obtained by fitting the tetrajet and dijet invariant mass distributions with a four-parameter dijet function and a search for local excesses from resonant production of dijet pairs is performed. No significant excess of events beyond the Standard Model expectation is observed, and upper limits are set on the production cross-sections of new physics scenarios.
We present a set of new generalized kinematic imbalance variables that can be measured in neutrino scattering. These variables extend previous measurements of kinematic imbalance on the transverse plane, and are more sensitive to modeling of nuclear effects. We demonstrate the enhanced power of these variables using simulation, and then use the MicroBooNE detector to measure them for the first time. We report flux-integrated single- and double-differential measurements of charged-current muon neutrino scattering on argon using a topolgy with one muon and one proton in the final state as a function of these novel kinematic imbalance variables. These measurements allow us to demonstrate that the treatment of charged current quasielastic interactions in GENIE version 2 is inadequate to describe data. Further, they reveal tensions with more modern generator predictions particularly in regions of phase space where final state interactions are important.
Experimental activities involving multi-TeV muon collisions are a relatively recent endeavor. The community has limited experience in designing detectors for lepton interactions at center-of-mass energies of 10 TeV and beyond. This review provides a short overview of the machine characteristics and outlines potential sources of beam-induced background that could impact the detector performance. The strategy for mitigating the effects of beam-induced background on the detector at $\sqrt{s}=3$ TeV is discussed, focusing on the machine-detector interface, detector design, and the implementation of reconstruction algorithms. The physics potential at this center-of-mass energy is evaluated using a detailed detector simulation that incorporates the effects of beam-induced background. This evaluation concerns the Higgs boson couplings and the Higgs field potential sensitivity, that then are used to get confidence on the expectations at 10 TeV. The physics and detector requirements for an experiment at $\sqrt{s}=10$ TeV, outlined here, form the foundation for the initial detector concept at that center-of-mass energy .
Large-scale optical neutrino and dark-matter detectors rely on large-area photomultiplier tubes (PMTs) for cost-effective light detection. The new R14688-100 8-inch PMT developed by Hamamatsu provides state-of-the-art timing resolution of around 1 ns (FWHM), which can help improve vertex reconstruction and enable Cherenkov and scintillation light separation in scintillation-based detectors. This PMT also provides excellent charge resolution, allowing for precision photoelectron counting and improved energy reconstruction. The Eos experiment is the first large-scale optical detector to utilize these PMTs. In this manuscript we present a characterization of the R14688-100 single photoelectron response, such as the transit-time spreads, the dark-rates, and the afterpulsing. The single photoelectron response measurements are performed for the 206 PMTs that will be used in Eos.
The transition into a strongly-correlated regime of 3 fermions trapped in a one-dimensional harmonic potential is investigated. This interesting, but little-studied system, allows us to identify characteristic features of the regime, some of which are also present in strongly-correlated materials relevant to the industry. Furthermore, our findings describe the behavior of electrons in quantum dots, ions in Paul traps, and even fermionic atoms in one-dimensional optical lattices. Near the ground state, all these platforms can be described as fermions trapped in a harmonic potential. The correlation regime can be controlled by varying the natural frequency of the trapping potential, and to probe it, we propose to use twisted light. We identify 4 signatures of strong correlation in the one-dimensional 3-fermion trap, which are likely to be present for any number N of trapped fermions: i) the ground state density is strongly localized with N maximally separated peaks (Wigner Crystal) ii) the symmetric and antisymmetric ground state wavefunctions become degenerate (bosonization) iii) the von Neumann entropy grows, iv) the energy spectrum is fully characterized by N normal modes or less.
In the context of quantum objectivity, a standard way to quantify the classicality of a state is via the mutual information between a system and different fractions of its environment. Many of the tools developed in the relevant literature to quantify quantum objectivity via quantum mutual information rely on the assumption that information about the system leaks symmetrically into its environment. In this work, we highlight the importance of taking this assumption into account, and in particular, analyse how taking non-averaged quantum mutual information as a quantifier of quantum objectivity can be severely misleading whenever information about the system is encoded into the environment in a non-homogeneous way. On the other hand, the averaged mutual information always provides results with a clear operative interpretation.
Variational quantum algorithms (VQAs) have demonstrated considerable potential in solving NP-hard combinatorial problems in the contemporary near intermediate-scale quantum (NISQ) era. The quantum approximate optimisation algorithm (QAOA) is one such algorithm, used in solving the maximum cut (Max-Cut) problem for a given graph by successive implementation of $L$ quantum circuit layers within a corresponding Trotterised ansatz. The challenge of exploring the cost function of VQAs arising from an exponential proliferation of local minima with increasing circuit depth has been well-documented. However, fewer studies have investigated the impact of circuit depth on QAOA performance in finding the correct Max-Cut solution. Here, we employ basin-hopping global optimisation methods to navigate the energy landscapes for QAOA ans\"atze for various graphs, and analyse QAOA performance in finding the correct Max-Cut solution. The structure of the solution space is also investigated using discrete path sampling to build databases of local minima and the transition states that connect them, providing insightful visualisations using disconnectivity graphs. We find that the corresponding landscapes generally have a single funnel organisation, which makes it relatively straightforward to locate low-lying minima with good Max-Cut solution probabilities. In some cases below the adiabatic limit the second lowest local minimum may even yield a higher solution probability than the global minimum. This important observation has motivated us to develop broader metrics in evaluating QAOA performance, based on collections of minima obtained from basin-hopping global optimisation. Hence we establish expectation thresholds in elucidating useful solution probabilities from local minima, an approach that may provide significant gains in elucidating reasonable solution probabilities from local minima.
Considering the growing interest in magnetic materials for unconventional computing, data storage, and sensor applications, there is active research not only on material synthesis but also characterisation of their properties. In addition to structural and integral magnetic characterisations, imaging of magnetization patterns, current distributions and magnetic fields at nano- and microscale is of major importance to understand the material responses and qualify them for specific applications. In this roadmap, we aim to cover a broad portfolio of techniques to perform nano- and microscale magnetic imaging using SQUIDs, spin center and Hall effect magnetometries, scanning probe microscopies, x-ray- and electron-based methods as well as magnetooptics and nanoMRI. The roadmap is aimed as a single access point of information for experts in the field as well as the young generation of students outlining prospects of the development of magnetic imaging technologies for the upcoming decade with a focus on physics, materials science, and chemistry of planar, 3D and geometrically curved objects of different material classes including 2D materials, complex oxides, semi-metals, multiferroics, skyrmions, antiferromagnets, frustrated magnets, magnetic molecules/nanoparticles, ionic conductors, superconductors, spintronic and spinorbitronic materials.
Exceptional-point (EP) sensors are characterized by a square-root resonant frequency bifurcation in response to an external perturbation. This has lead numerous suggestions for using these systems for sensing applications. However, there is an open debate as to whether or not this sensitivity advantage is negated by additional noise in the system. We show that an EP sensor's imprecision in measuring a generalized force is independent of its operating point's proximity to the EP. That is because frequency noises of fundamental origin in the sensor -- due to quantum and thermal fluctuations -- increase in a manner that exactly cancels the benefit of increased resonant frequency sensitivity near the EP. So the benefit of EP sensors is limited to the regime where sensing is limited by technical noises. Finally, we outline an EP sensor with phase-sensitive gain that does have an advantage even if limited by fundamental noises.
An emergent and promising tensor-network-based impurity solver is to represent the path integral as a matrix product state, where the bath is analytically integrated out using Feynman-Vernon influence functional. Here we present an approach to calculate the equilibrium impurity spectral function based on the recently proposed Grassmann time-evolving matrix product operators method. The central idea is to perform a quench from a separable impurity-bath initial state as in the non-equilibrium scenario. The retarded Green's function $G(t+t_0, t'+t_0)$ is then calculated after an equilibration time $t_0$ such that the impurity and bath are approximately in thermal equilibrium. There are two major advantages of this method. First, since we focus on real-time dynamics, we do not need to perform the numerically ill-posed analytic continuation in the continuous-time quantum Monte Carlo case that relies on imaginary-time evolution. Second, the entanglement growth of the matrix product states in real-time calculations is observed to be much slower than that in imaginary-time calculations, leading to a significant improvement in numerical efficiency. The accuracy of this method is demonstrated in the single-orbital Anderson impurity model and benchmarked against the continuous-time quantum Monte Carlo method.
The dynamics of the interaction between an atom of three levels interacting with a quantized field of two modes in a cavity is studied within the rotating wave approximation by taking into account experimental values of the accessible hyperfine levels of alkaline atoms. An equal detuning is considered to determine the matter-field entanglement, the statistical properties of the photons, and the occupation probabilities of the atom. For a large detuning or weak dipolar strength appears, the Raman condition, that is, the suppression of one of his atomic transitions. Analytical expression for the time evolution operator allows to have also explicit closed expressions for the field and matter observables.
Optical tweezers constitute pivotal tools in Atomic, Molecular, and Optical(AMO) physics, facilitating precise trapping and manipulation of individual atoms and molecules. This process affords the capability to generate desired geometries in both one-dimensional and two-dimensional spaces, while also enabling real-time reconfiguration of atoms. Due to stochastic defects in these tweezers, which cause catastrophic performance degradation especially in quantum computations, it is essential to rearrange the tweezers quickly and accurately. Our study introduces a machine learning approach that uses the Proximal Policy Optimization model to optimize this rearrangement process. This method focuses on efficiently solving the shortest path problem, ensuring the formation of defect-free tweezer arrays. By implementing machine learning, we can calculate optimal motion paths under various conditions, resulting in promising results in model learning. This advancement presents new opportunities in tweezer array rearrangement, potentially boosting the efficiency and precision of quantum computing research.
The variational quantum eigensolver (VQE) framework has been instrumental in advancing near-term quantum algorithms. However, parameter optimization remains a significant bottleneck for VQE, requiring a large number of measurements for successful algorithm execution. In this paper, we propose sequential optimization with approximate parabola (SOAP) as an efficient and robust optimizer specifically designed for parameter optimization of the unitary coupled-cluster ansatz on quantum computers. SOAP leverages sequential optimization and approximates the energy landscape as quadratic functions, minimizing the number of energy evaluations required to optimize each parameter. To capture parameter correlations, SOAP incorporates the average direction from the previous iteration into the optimization direction set. Numerical benchmark studies on molecular systems demonstrate that SOAP achieves significantly faster convergence and greater robustness to noise compared to traditional optimization methods. Furthermore, numerical simulations up to 20 qubits reveal that SOAP scales well with the number of parameters in the ansatz. The exceptional performance of SOAP is further validated through experiments on a superconducting quantum computer using a 2-qubit model system.
Phase-sensitive amplification of squeezed states is a technique to mitigate high detection loss, e.g. at 2-micrometre wavelengths. Our analytical model of amplified squeezed states expands on the effect of phase noise and derives two practical parameters: the effective measurable squeezing and the effective detection efficiency. A case study including realistic parameters demonstrates the benefit of phase-sensitive amplification. We identified the phase noise in the optical parametric amplifier (OPA) minimally affects the squeezing level, enabling increased gain of the OPA. This scheme is compatible with proposed gravitational-wave detectors and consistent with applications in quantum systems that are degraded by output coupling loss in optical waveguides.
We present an experimental demonstration of balanced heterodyne readout that circumvents the 3 dB heterodyne signal-to-noise penalty on a dual Michelson sensor. Our readout obtains both amplitude and phase quadrature information simultaneously. We also employ a high-frequency spectrally entangled, two-mode squeezed state to show further signal-to-noise improvement of an injected audio-band signal. We achieve a quantum enhancement of 3.5 dB, consistent with our experimental efficiencies and dephasing. This technique is applicable for quantum-limited high-precision experiments, with application to searches for quantum gravity, gravitational wave detection and wavelength-multiplexed quantum communication.
The interaction of light and matter at the single-photon level is of central importance in various fields of physics, including, e.g., condensed matter physics, astronomy, quantum optics, and quantum information. Amplification of such quantum light-matter interaction can be highly beneficial to, e.g., improve device performance, explore novel phenomena, and understand fundamental physics, and has therefore been a long-standing goal. Furthermore, simulation of light-matter interaction in the regime of ultrastrong coupling, where the interaction strength is comparable to the bare frequencies of the uncoupled systems, has also become a hot research topic, and considerable progress has been made both theoretically and experimentally in the past decade. In this review, we provide a detailed introduction of recent advances in amplification of quantum light-matter interaction and simulation of ultrastrong light-matter interaction, particularly in cavity and circuit quantum electrodynamics and in cavity optomechanics.
Quantum metrology has been shown to surpass classical limits of correlation, resolution, and sensitivity. It has been introduced to interferometric Radar schemes, with intriguing preliminary results. Even quantum-inspired detection of classical signals may be advantageous in specific use cases. Following ideas demonstrated so far only in the optical domain, where practically no thermal background photons exist, we realize room-temperature microwave frequency super-resolved phase measurements with trillions of photons, while saturating the Cramer-Rao bound of sensitivity. We experimentally estimate the interferometric phase using the expectation value of the Parity operator by two methods. We achieve super-resolution up to 1200 times better than the wavelength with 25ns integration time and 56dB SNR.
Random matrix theory is a powerful tool for understanding spectral correlations inherent in quantum chaotic systems. Despite diverse applications of non-Hermitian random matrix theory, the role of symmetry remains to be fully established. Here, we comprehensively investigate the impact of symmetry on the level statistics around the spectral origin -- hard-edge statistics -- and complete the classification of spectral statistics in all the 38 symmetry classes of non-Hermitian random matrices. Within this classification, we discern 28 symmetry classes characterized by distinct hard-edge statistics from the level statistics in the bulk of spectra, which are further categorized into two groups, namely the Altland-Zirnbauer$_0$ classification and beyond. We introduce and elucidate quantitative measures capturing the universal hard-edge statistics for all the symmetry classes. Furthermore, through extensive numerical calculations, we study various open quantum systems in different symmetry classes, including quadratic and many-body Lindbladians, as well as non-Hermitian Hamiltonians. We show that these systems manifest the same hard-edge statistics as random matrices and that their ensemble-average spectral distributions around the origin exhibit emergent symmetry conforming to the random-matrix behavior. Our results establish a comprehensive understanding of non-Hermitian random matrix theory and are useful in detecting quantum chaos or its absence in open quantum systems.
Unital qubit Schwarz maps interpolate between positive and completely positive maps. It is shown that relaxation rates of qubit semigroups of unital maps enjoying Schwarz property satisfy the universal constraint which provides a modification of the corresponding constraint known for completely positive semigroups. As an illustration we consider two paradigmatic qubit semigroups: Pauli dynamical maps and phase covariant dynamics. This result has two interesting implications: it provides a universal constraint for the spectra of qubit Schwarz maps and gives rise to a necessary condition for a Schwarz qubit map to be Markovian.
Antimicrobial peptides (AMPs) play important roles in cancer, autoimmune diseases, and aging. A critical aspect of AMP functionality is their targeted interaction with pathogen membranes, which often possess altered lipid compositions. Designing AMPs with enhanced therapeutic properties relies on a nuanced understanding of these interactions, which are believed to trigger a rearrangement of these peptides from random coil to alpha-helical conformations, essential for their lytic action. Traditional supercomputing has consistently encountered difficulties in accurately modeling these structural changes, especially within membrane environments, thereby opening an opportunity for more advanced approaches. This study extends an existing quantum computing algorithm to address the complexities of antimicrobial peptide interactions at interfaces. Our approach enables the prediction of the optimal conformation of peptides located in the transition region between hydrophilic and hydrophobic phases, akin to lipid membranes. The new method has been applied to model the structure of three 10-amino-acid-long peptides, each exhibiting hydrophobic, hydrophilic, or amphipathic properties in different media and at interfaces between solvents of different polarity. Notably, our approach does not demand a higher number of qubits compared to simulations in homogeneous media, making it more feasible with current quantum computing resources. Despite existing limitations in computational power and qubit accessibility, our findings demonstrate the significant potential of quantum computing in accurately characterizing complex biomolecular processes, particularly the folding of AMPs at membrane models. This research paves the way for future advances in quantum computing to enhance the accuracy and applicability of biomolecular simulations.
Efficient optical quantum memories are a milestone required for several quantum technologies including repeater-based quantum key distribution and on-demand multi-photon generation. We present an efficiency optimization of an optical electromagnetically induced transparency (EIT) memory experiment in a warm cesium vapor using a genetic algorithm and analyze the resulting waveforms. The control pulse is represented either as a Gaussian or free-form pulse, and the results from the optimization are compared. We see an improvement factor of 3(7)\% when using optimized free-form pulses. By limiting the allowed pulse energy in a solution, we show an energy-based optimization giving a 30% reduction in energy, with minimal efficiency loss.
Ultracold molecules confined in optical lattices or tweezer traps can be used to process quantum information and simulate the behaviour of many-body quantum systems. Molecules offer several advantages for these applications. They have a large set of stable states with strong transitions between them and long coherence times. They can be prepared in a chosen state with high fidelity, and the state populations can be measured efficiently. They have controllable long-range dipole-dipole interactions that can be used to entangle pairs of molecules and generate interesting many-body states. We review the advances that have been made and the challenges still to overcome, and describe the new ideas that will unlock the full potential of the field.
Nonreciprocity, arising from the breaking of time-reversal symmetry, has become a fundamental tool in diverse quantum technology applications. It enables directional flow of signals and efficient noise suppression, constituting a key element in the architecture of current quantum information and computing systems. Here we explore its potential in optimizing the charging dynamics of a quantum battery. By introducing nonreciprocity through reservoir engineering during the charging process, we induce a directed energy flow from the quantum charger to the battery, resulting in a substantial increase in energy accumulation. Despite local dissipation, the nonreciprocal approach demonstrates a fourfold increase in battery energy compared to conventional charger-battery systems. We demonstrate that employing a shared reservoir can establish an optimal condition where nonreciprocity enhances charging efficiency and elevates energy storage in the battery. This effect is observed in the stationary limit and remains applicable even in overdamped coupling regimes, eliminating the need for precise temporal control over evolution parameters. Our result can be extended to a chiral network of quantum nodes, serving as a multi-cell quantum battery system to enhance storage capacity. The proposed approach is straightforward to implement using current state-of-the-art quantum circuits, both in photonics and superconducting quantum systems. In a broader context, the concept of nonreciprocal charging has significant implications for sensing, energy capture, and storage technologies or studying quantum thermodynamics.
We study mixed unitary channels generated by finite subgroups of the group of all unitary operators in a Hilbert space. Based on the majorization theory we introduce techniques allowing to calculate different characteristics of output states of channels. A class of channels has been allocated for which the use of entangled states doesn't give any advantage under taking supremum and infimum for output characteristics of channels. In particular, $l_p$-norms are multiplicative and the minimal entropy is additive with respect to taking tensor products of channels. As an important application of the obtained results the classical capacity of channel is calculated in the evident form. We compare our techniques with the informational characteristics of Boson quantum channels.
The coupling of an isolated quantum state to a continuum is typically associated with decoherence and decreased lifetime. Here, we demonstrate that Rydberg macrodimers, weakly bound pairs of Rydberg atoms, can overcome this dissipative mechanism and instead form bound states with the continuum of free motional states. This is enabled by the unique combination of extraordinarily slow vibrational motion in the molecular state and the optical coupling to a non-interacting continuum. Under conditions of strong coupling, we observe the emergence of distinct resonances and explain them within a Fano model. For atoms arranged on a lattice, we predict the strong continuum coupling to even stabilize molecules consisting of more than two atoms and find first signatures of these by observing atom loss correlations using a quantum gas microscope. Our results present an intriguing mechanism to control decoherence and bind multiatomic molecules using strong light-matter interactions.
Adaptive protocols enable the construction of more efficient state preparation circuits in variational quantum algorithms (VQAs) by utilizing data obtained from the quantum processor during the execution of the algorithm. This idea originated with ADAPT-VQE, an algorithm that iteratively grows the state preparation circuit operator by operator, with each new operator accompanied by a new variational parameter, and where all parameters acquired thus far are optimized in each iteration. In ADAPT-VQE and other adaptive VQAs that followed it, it has been shown that initializing parameters to their optimal values from the previous iteration speeds up convergence and avoids shallow local traps in the parameter landscape. However, no other data from the optimization performed at one iteration is carried over to the next. In this work, we propose an improved quasi-Newton optimization protocol specifically tailored to adaptive VQAs. The distinctive feature in our proposal is that approximate second derivatives of the cost function are recycled across iterations in addition to parameter values. We implement a quasi-Newton optimizer where an approximation to the inverse Hessian matrix is continuously built and grown across the iterations of an adaptive VQA. The resulting algorithm has the flavor of a continuous optimization where the dimension of the search space is augmented when the gradient norm falls below a given threshold. We show that this inter-optimization exchange of second-order information leads the Hessian in the state of the optimizer to better approximate the exact Hessian. As a result, our method achieves a superlinear convergence rate even in situations where the typical quasi-Newton optimizer converges only linearly. Our protocol decreases the measurement costs in implementing adaptive VQAs on quantum hardware as well as the runtime of their classical simulation.
Based on earlier work by Carlen-Maas and the second- and third-named author, we introduce the notion of intertwining curvature lower bounds for graphs and quantum Markov semigroups. This curvature notion is stronger than both Bakry-\'Emery and entropic Ricci curvature, while also computationally simpler than the latter. We verify intertwining curvature bounds in a number of examples, including finite weighted graphs and graphs with Laplacians admitting nice mapping representations, as well as generalized dephasing semigroups and quantum Markov semigroups whose generators are formed by commuting jump operators. By improving on the best-known bounds for entropic curvature of depolarizing semigroups, we demonstrate that there can be a gap between the optimal intertwining and entropic curvature bound. In the case of qubits, this improved entropic curvature bound implies the modified logarithmic Sobolev inequality with optimal constant.
We show the targeted phase-manipulation of an entangled photonic Bell state via non-inertial motion. To this end, we place a very compact laboratory, consisting of a SPDC source and a Sagnac interferometer, on a rotating platform (non-inertial reference frame). The photon pairs of a $\ket{\phi}$-state are in a superposition of co- and counter-rotation. The phase of the $\ket{\phi}$-state is linearly dependent on the angular velocity of the rotating platform due to the Sagnac effect. We measure the visibility and certify entanglement with the Bell-CHSH parameter $S$. Additionally, we conduct a partial quantum state tomography on the Bell states in a non-inertial environment. Our experiment showcases the unitary transformation of an entangled state via non-inertial motion and constitutes not only a switch between a $\ket{\phi^{-}}$-state and a $\ket{\phi^{+}}$-state but also a further experiment at the interplay of non-inertial motion and quantum physics.
We study the mixed-type classical dynamics of the three-particle Fermi-Pasta-Ulam-Tsingou (FPUT) model in relationship with its quantum counterpart, and present new results on aspects of quantum chaos in this system. First we derive for the general N-particle FPUT system the transformation to the normal mode representation. Then we specialize to the three-particle FPUT case, and derive analytically the semiclassical energy density of states, and its derivatives in which different singularies are determined, using the Thomas-Fermi rule. The result perfectly agrees with the numerical energy density from the Krylov subspace method, as well as with the energy density obtained by the method of quantum typicality. Here, in paper I, we concentrate on the energy level statistics (level spacing and spacing ratios), in all classical dynamical regimes of interest: the almost entirely regular, the entirely chaotic, and the mixed-type regimes. We clearly confirm, correspondingly, the Poissonian statistics, the GOE statistics, and the Berry-Robnik-Brody (BRB) statistics in the mixed-type regime. It is found that the BRB level spacing distribution perfectly fits the numerical data. The extracted quantum Berry-Robnik parameter is found to agree with the classical value within better than one percent. We discuss the role of localization of chaotic eigenstates, and its appearances, in relation to the classical phase space structure (Poincar\'e and SALI plots), whose details will be presented in paper II, where the structure and the statistical properties of the Husimi functions in the quantum phase space will be studied.
Test of {macroscopic realism} (MR) is key to understanding the foundation of quantum mechanics. Due to the existence of the {non-invasive measurability} loophole and other interpretation loopholes, however, such test remains an open question. Here we propose a general inequality based on high-order correlations of measurements for a loophole-free test of MR at the weak signal limit. Importantly, the inequality is established using the statistics of \textit{raw data} recorded by classical devices, without requiring a specific model for the measurement process, so its violation would falsify MR without the interpretation loophole. The non-invasive measurability loophole is also closed, since the weak signal limit can be verified solely by measurement data (using the relative scaling behaviors of different orders of correlations). We demonstrate that the inequality can be broken by a quantum spin model. The inequality proposed here provides an unambiguous test of the MR principle and is also useful to characterizing {quantum coherence}.
Tilted lattice potentials with periodic driving play a crucial role in the study of artificial gauge fields and topological phases with ultracold quantum gases. However, driving-induced heating and the growth of phonon modes restrict their use for probing interacting many-body states. Here, we experimentally investigate phonon modes and interaction-driven instabilities of superfluids in the lowest band of a shaken optical lattice. We identify stable and unstable parameter regions and provide a general resonance condition. In contrast to the high-frequency approximation of a Floquet description, we use the superfluids' micromotion to analyze the growth of phonon modes from slow to fast driving frequencies. Our observations enable the prediction of stable parameter regimes for quantum-simulation experiments aimed at studying driven systems with strong interactions over extended time scales.
This research aims to model tracks the evolution of opinions among agents and their collective dynamics, and mathematically represents the resonance of opinions and echo chamber effects within the filter bubble by including non-physical factors such as misinformation and confirmation bias, known as FP ghosting phenomena.The indeterminate ghost phenomenon, a social science concept similar to the uncertainty principle, depicts the variability of social opinion by incorporating information uncertainty and nonlinearities in opinion formation into the model. Furthermore, by introducing the Kubo formula and the Matsubara form of the Green's function, we mathematically express temporal effects and model how past, present, and future opinions interact to reveal the mechanisms of opinion divergence and aggregation. Our model uses multiple parameters, including population density and extremes of opinion generated on a random number basis, to simulate the formation and growth of filter bubbles and their progression to ultraviolet divergence phenomena. In this process, we observe how resonance or disconnection of opinions within a society occurs via a disconnection function (type la, lb, ll, lll). However, the interpretation of the results requires careful consideration, and empirical verification is a future challenge.Finally, we will share our hypotheses and considerations for the model case of this paper, which is a close examination of regional differences in media coverage and its effectiveness and considerations unique to Japan, a disaster-prone country.
Collective effects on the light scattered by disordered media such as Anderson localization and coherent backscattering critically depend on the reciprocity between interfering optical paths. In this work, we explore the breaking of reciprocity for the light scattered by a disordered cold atom setup, taking advantage of the non-commutation of optical elements that manipulate the polarization of the interfering paths. This breaking of symmetry manifests itself in the reduction of the fringes contrast as the light scattered by the cloud interferes with that from its mirror image. We provide a geometrical interpretation in terms of the Pancharatnam-Berry phase, which we directly access from the fringes displacement. Our work paves the way toward the manipulation of path reciprocity and interference for light scattered by disordered media.
In [Nat. Phys. 8, 325-330 (2012)], Trotzky et al. utilize ultracold atoms in an optical lattice to simulate the local relaxation dynamics of a strongly interacting Bose gas "for longer times than present classical algorithms can keep track of". Here, I classically verify the results of this analog quantum simulator by calculating the evolution of the same quasi-local observables up to the time at which they appear "fully relaxed". Using a parallel implementation of the time-evolving block decimation (TEBD) algorithm to simulate the system on a supercomputer, I show that local densities and currents can be calculated in a matter of days rather than weeks. The precision of these numerics allows me to observe deviations from the conjectured power-law decay and to determine the effects of the harmonic trapping potential. As well as providing a robust benchmark for future experimental, theoretical, and numerical methods, this work serves as an example of the independent verification process.
Recent advances in quantum information science have shed light on the intricate dynamics of quantum many-body systems, for which quantum information scrambling is a perfect example. Motivated by considerations of the thermodynamics of quantum information, this perspective aims at synthesizing key findings from several pivotal studies and exploring various aspects of quantum scrambling. We consider quantifiers such as the Out-of-Time-Ordered Correlator (OTOC), the quantum Mutual Information, and the Tripartite Mutual Information (TMI), their connections to thermodynamics, and their role in understanding chaotic versus integrable quantum systems. With a focus on representative examples, we cover a range of topics, including the thermodynamics of quantum information scrambling, and the scrambling dynamics in quantum gravity models such as the Sachdev-Ye-Kitaev (SYK) model. Examining these diverse approaches enables us to highlight the multifaceted nature of quantum information scrambling and its significance in understanding the fundamental aspects of quantum many-body dynamics at the intersection of quantum mechanics and thermodynamics.
One promising field of quantum computation is the simulation of quantum systems, and specifically, the task of ground state energy estimation (GSEE). Ground state preparation (GSP) is a crucial component in GSEE algorithms, and classical methods like Hartree-Fock state preparation are commonly used. However, the efficiency of such classical methods diminishes exponentially with increasing system size in certain cases. In this study, we investigated whether in those cases quantum heuristic GSP methods could improve the overlap values compared to Hartree-Fock. Moreover, we carefully studied the performance gain for GSEE algorithms by exploring the trade-off between the overlap improvement and the associated resource cost in terms of T-gates of the GSP algorithm. Our findings indicate that quantum heuristic GSP can accelerate GSEE tasks, already for computationally affordable strongly-correlated systems of intermediate size. These results suggest that quantum heuristic GSP has the potential to significantly reduce the runtime requirements of GSEE algorithms, thereby enhancing their suitability for implementation on quantum hardware.
We consider the time and space required for quantum computers to solve a wide variety of problems involving matrices, many of which have only been analyzed classically in prior work. Our main results show that for a range of linear algebra problems -- including matrix-vector product, matrix inversion, matrix multiplication and powering -- existing classical time-space tradeoffs, several of which are tight for every space bound, also apply to quantum algorithms. For example, for almost all matrices $A$, including the discrete Fourier transform (DFT) matrix, we prove that quantum circuits with at most $T$ input queries and $S$ qubits of memory require $T=\Omega(n^2/S)$ to compute matrix-vector product $Ax$ for $x \in \{0,1\}^n$. We similarly prove that matrix multiplication for $n\times n$ binary matrices requires $T=\Omega(n^3 / \sqrt{S})$. Because many of our lower bounds match deterministic algorithms with the same time and space complexity, we show that quantum computers cannot provide any asymptotic advantage for these problems with any space bound. We obtain matching lower bounds for the stronger notion of quantum cumulative memory complexity -- the sum of the space per layer of a circuit. We also consider Boolean (i.e. AND-OR) matrix multiplication and matrix-vector products, improving the previous quantum time-space tradeoff lower bounds for $n\times n$ Boolean matrix multiplication to $T=\Omega(n^{2.5}/S^{1/3})$ from $T=\Omega(n^{2.5}/S^{1/2})$. Our improved lower bound for Boolean matrix multiplication is based on a new coloring argument that extracts more from the strong direct product theorem used in prior work. Our tight lower bounds for linear algebra problems require adding a new bucketing method to the recording-query technique of Zhandry that lets us apply classical arguments to upper bound the success probability of quantum circuits.
Charged quasiparticles dressed by the low excitations of an electron gas, constitute one of the fundamental pillars for understanding quantum many-body effects in some materials. Quantum simulation of quasiparticles arising from atom-ion hybrid systems may shed light on solid-state uncharted regimes. Here we investigate the ionic Fermi polaron consisting of a charged impurity interacting with a polarized Fermi bath. Employing state-of-the-art quantum Monte Carlo techniques tailored for strongly correlated systems, we characterize the charged quasiparticle by computing the energy spectrum, quasiparticle residue, and effective mass, as well as the structural properties of the system. Our findings in the weak coupling regime agree with field-theory predictions within the ladder approximation. However, stark deviations emerge in the strongly interacting regime attributed to the vastly large density inhomogeneity around the ion, resulting in strong correlations for distances on the order of the atom-ion potential range. Moreover, we find a smooth polaron-molecule transition for strong coupling, in contrast with the neutral case, where the transition smoothens only for finite temperature and finite impurity density. This study may provide valuable insights into alternative solid-state systems such as Fermi excitons polarons in atomically thin semiconductors beyond the short-range limit.
We propose a general mechanism for generating limit cycle (LC) oscillations by coupling a linear bosonic mode to a dissipative nonlinear bosonic mode. By analyzing the stability matrix, we show that LCs arise due to a supercritical Hopf bifurcation. We find that the existence of LCs is independent of the sign of the effective nonlinear interaction. The LC phase can be classified as a continuous time crystal (CTC), if it emerges in a many-body system. The bosonic model can be realised in three-level systems interacting with a quantised light mode as realised in atom-cavity systems. Using such a platform, we experimentally observe LCs for the first time in an atom-cavity system with attractive optical pump lattice, thereby confirming our theoretical predictions.
Special approximation technique for analysis of different characteristics of states of multipartite infinite-dimensional quantum systems is proposed and applied to study of the relative entropy of entanglement and its regularisation. We prove several results about analytical properties of the multipartite relative entropy of entanglement and its regularization (the lower semicontinuity on wide class of states, the uniform continuity under the energy constraints, etc.). We establish a finite-dimensional approximation property for the relative entropy of entanglement and its regularization that allows to generalize to the infinite-dimensional case the results proved in the finite-dimensional settings.
It has been a long-standing open problem to construct a general framework for relating the spectra of dual theories to each other. Here, we solve this problem for the case of one-dimensional quantum lattice models with symmetry-twisted boundary conditions. In ref. [PRX Quantum 4, 020357], dualities are defined between (categorically) symmetric models that only differ in a choice of module category. Using matrix product operators, we construct from the data of module functors explicit symmetry operators preserving boundary conditions as well as intertwiners mapping topological sectors of dual models onto one another. We illustrate our construction with a family of examples that are in the duality class of the spin-$\frac{1}{2}$ Heisenberg XXZ model. One model has symmetry operators forming the fusion category $\mathsf{Rep}(\mathcal S_3)$ of representations of the group $\mathcal S_3$. We find that the mapping between its topological sectors and those of the XXZ model is associated with the non-trivial braided auto-equivalence of the Drinfel'd center of $\mathsf{Rep}(\mathcal S_3)$.
Large-scale quantum computers will inevitably need quantum error correction (QEC) to protect information against decoherence. Given that the overhead of such error correction is often formidable, autonomous quantum error correction (AQEC) proposals offer a promising near-term alternative. AQEC schemes work by transforming error states into excitations that can be efficiently removed through engineered dissipation. The recently proposed AQEC scheme by Li et al., called the Star code, can autonomously correct or suppress all single qubit error channels using two transmons as encoders with a tunable coupler and two lossy resonators as a cooling source. The Star code requires only two-photon interactions and can be realized with linear coupling elements, avoiding experimentally challenging higher-order terms needed in many other AQEC proposals, but needs carefully selected parameters to achieve quadratic improvements in logical states' lifetimes. Here, we theoretically and numerically demonstrate the optimal parameter choices in the Star Code. We further discuss adapting the Star code to other planar superconducting circuits, which offers a scalable alternative to single qubits for incorporation in larger quantum computers or error correction codes.
Supervised quantum learning is an emergent multidisciplinary domain bridging between variational quantum algorithms and classical machine learning. Here, we study experimentally a hybrid classifier model accelerated by a quantum simulator - a linear array of four superconducting transmon artificial atoms - trained to solve multilabel classification and image recognition problems. We train a quantum circuit on simple binary and multi-label tasks, achieving classification accuracy around 95%, and a hybrid model with data re-uploading with accuracy around 90% when recognizing handwritten decimal digits. Finally, we analyze the inference time in experimental conditions and compare the performance of the studied quantum model with known classical solutions.
Quantum Approximate Optimization Algorithm (QAOA) is a leading candidate algorithm for solving combinatorial optimization problems on quantum computers. However, in many cases QAOA requires computationally intensive parameter optimization. The challenge of parameter optimization is particularly acute in the case of weighted problems, for which the eigenvalues of the phase operator are non-integer and the QAOA energy landscape is not periodic. In this work, we develop parameter setting heuristics for QAOA applied to a general class of weighted problems. First, we derive optimal parameters for QAOA with depth $p=1$ applied to the weighted MaxCut problem under different assumptions on the weights. In particular, we rigorously prove the conventional wisdom that in the average case the first local optimum near zero gives globally-optimal QAOA parameters. Second, for $p\geq 1$ we prove that the QAOA energy landscape for weighted MaxCut approaches that for the unweighted case under a simple rescaling of parameters. Therefore, we can use parameters previously obtained for unweighted MaxCut for weighted problems. Finally, we prove that for $p=1$ the QAOA objective sharply concentrates around its expectation, which means that our parameter setting rules hold with high probability for a random weighted instance. We numerically validate this approach on general weighted graphs and show that on average the QAOA energy with the proposed fixed parameters is only $1.1$ percentage points away from that with optimized parameters. Third, we propose a general heuristic rescaling scheme inspired by the analytical results for weighted MaxCut and demonstrate its effectiveness using QAOA with the XY Hamming-weight-preserving mixer applied to the portfolio optimization problem. Our heuristic improves the convergence of local optimizers, reducing the number of iterations by 7.4x on average.
Light from any physical source diffracts over space, as spherical wavefronts grow and energy density is spread out. Diffractive effects pose fundamental limits to light-based technologies, including communications, spectroscopy, and metrology. Polarisation becomes paraxial in the far field limit and, by ignoring longitudinal field components, the rich physics of non-paraxial fields which exist in near-fields or a beam's tight focus are lost. The longitudinal field cannot, however, be ignored when transverse field components vanish (in a transverse field zero) and carry a small non-paraxial region to infinity. We show that a transverse field zero is always accompanied by non-diffracting polarisation structures, whose geometries are independent of the distance to the source, including an enclosing intensity ratio tube, and parallel, non-diverging polarisation singularities. We illustrate these features in multipole radiation and in double slit interference, two examples which have time-fixed transverse field zeros. Non-diffracting structures with changing position are coupled to time-varying zeros, which are present in all far field radiation.
It is shown that the atomic inversion in the Jaynes-Cummings model has an exact representation as an integral over the Hankel contour. For a field in a coherent state, the integral is evaluated using the saddle point method. The trajectories of saddle points as a function of time are on the branches of the multi-valued Lambert function. All of them start at the initial moment of time, but make the maximum contribution to the inversion at different times. If the collapse and the first revival are clearly distinguished, then subsequent revivals are determined by the comparable contributions of several trajectories.
A major obstacle for quantum optimizers is the reformulation of constraints as a quadratic unconstrained binary optimization (QUBO). Current QUBO translators exaggerate the weight $M$ of the penalty terms. Classically known as the "Big-$M$" problem, the issue becomes even more daunting for quantum solvers, since it affects the physical energy scale. We take a systematic, encompassing look at the quantum big-$M$ problem, revealing NP-hardness in finding the optimal $M$ and establishing bounds on the Hamiltonian spectral gap $\Delta$, inversely related to the expected run-time of quantum solvers. We propose a practical translation algorithm, based on SDP relaxation, that outperforms previous methods in numerical benchmarks. Our algorithm gives values of $\Delta$ orders of magnitude greater, e.g. for portfolio optimization instances. Solving such instances with an adiabatic algorithm on 6-qubits of an IonQ device, we observe significant advantages in time to solution and average solution quality. Our findings are relevant to quantum and quantum-inspired solvers alike.
Loading functions into quantum computers represents an essential step in several quantum algorithms, such as quantum partial differential equation solvers. Therefore, the inefficiency of this process leads to a major bottleneck for the application of these algorithms. Here, we present and compare two efficient methods for the amplitude encoding of real polynomial functions on $n$ qubits. This case holds special relevance, as any continuous function on a closed interval can be uniformly approximated with arbitrary precision by a polynomial function. The first approach relies on the matrix product state representation. We study and benchmark the approximations of the target state when the bond dimension is assumed to be small. The second algorithm combines two subroutines. Initially we encode the linear function into the quantum registers with a swallow sequence of multi-controlled gates that loads the linear function's Hadamard-Walsh series, exploring how truncating the Hadamard-Walsh series of the linear function affects the final fidelity. Applying the inverse discrete Hadamard-Walsh transform transforms the series coefficients into an amplitude encoding of the linear function. Then, we use this construction as a building block to achieve a block encoding of the amplitudes corresponding to the linear function on $k_0$ qubits and apply the quantum singular value transformation that implements a polynomial transformation to the block encoding of the amplitudes. This unitary together with the Amplitude Amplification algorithm will enable us to prepare the quantum state that encodes the polynomial function on $k_0$ qubits. Finally we pad $n-k_0$ qubits to generate an approximated encoding of the polynomial on $n$ qubits, analyzing the error depending on $k_0$. In this regard, our methodology proposes a method to improve the state-of-the-art complexity by introducing controllable errors.
We generalize L\'evy's lemma, a concentration-of-measure result for the uniform probability distribution on high-dimensional spheres, to a much more general class of measures, so-called GAP measures. For any given density matrix $\rho$ on a separable Hilbert space $\mathcal{H}$, GAP$(\rho)$ is the most spread out probability measure on the unit sphere of $\mathcal{H}$ that has density matrix $\rho$ and thus forms the natural generalization of the uniform distribution. We prove concentration-of-measure whenever the largest eigenvalue $\|\rho\|$ of $\rho$ is small. We use this fact to generalize and improve well-known and important typicality results of quantum statistical mechanics to GAP measures, namely canonical typicality and dynamical typicality. Canonical typicality is the statement that for ``most'' pure states $\psi$ of a given ensemble, the reduced density matrix of a sufficiently small subsystem is very close to a $\psi$-independent matrix. Dynamical typicality is the statement that for any observable and any unitary time-evolution, for ``most'' pure states $\psi$ from a given ensemble the (coarse-grained) Born distribution of that observable in the time-evolved state $\psi_t$ is very close to a $\psi$-independent distribution. So far, canonical typicality and dynamical typicality were known for the uniform distribution on finite-dimensional spheres, corresponding to the micro-canonical ensemble, and for rather special mean-value ensembles. Our result shows that these typicality results hold in general for systems described by a density matrix $\rho$ with small eigenvalues. Since certain GAP measures are quantum analogs of the canonical ensemble of classical mechanics, our results can also be regarded as a version of equivalence of ensembles.
A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dependent control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by $\sim3.7\times$ compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures.
We study quantum dynamics in phase space for a continuous single mode system which is entangled with another such mode. As our main example we use the strongly mode mixing dynamics of a variable beam splitter which makes the dynamics of each mode conditional on the other mode. We derive and study the form of the conditional Wigner current J of one mode after tracing out the other. Since in other representations of quantum theory no analogue for J exists, only the phase space representation can be used for this type of visual study of such conditional dynamics.
Recently, the quantum spin-Hall edge channels of two-dimensional colloidal nanocrystals of the topological insulator Bi$_2$Se$_3$ were observed directly. Motivated by this development, we reconsider the four-band effective model which has been traditionally employed in the past to describe thin nanosheets of this material. Derived from a three-dimensional $\boldsymbol{k} \boldsymbol{\cdot} \boldsymbol{p}$ model, it physically describes the top and bottom electronic surface states that become gapped due to the material's small thickness. However, we find that the four-band model for the surface states alone, as derived directly from the three-dimensional theory, is inadequate for the description of thin films of a few quintuple layers and even yields an incorrect topological invariant within a significant range of thicknesses. To address this limitation we propose an eight-band model which, in addition to the surface states, also incorporates the set of bulk bands closest to the Fermi level. We find that the eight-band model not only captures most of the experimental observations, but also agrees with previous first-principles calculations of the $\mathbb{Z}_{2}$ invariant in thin films of varying thickness. Moreover, we demonstrate that the topological properties of thin Bi$_2$Se$_3$ nanosheets emerge as a result of an intricate interplay between the surface and bulk states. In particular, the surface bands of the eight-band model differ drastically from their counterparts in their four-band model, with the missing topology of the latter restored by the newly added bulk bands.
We give a vacuum description with zero-point density for virtual fluctuations. One of the goals is to explain the origin of the vacuum permittivity and permeability and to calculate their values. In particular, we improve on existing calculations by avoiding assumptions on the volume occupied by virtual fluctuations. We propose testing of the models that assume a finite lifetime of virtual fluctuation. If during its propagation, the photon is stochastically trapped and released by virtual pairs, the propagation velocity may fluctuate. The propagation time fluctuation is estimated for several existing models. The obtained values are measurable with available technologies involving ultra-short laser pulses, and some of the models are already in conflict with the existing astronomical observations. The phase velocity is not affected significantly, which is consistent with the interferometric measurements.
This paper reports an inductorless transimpedance amplifier (TIA) with very compact size and adequate performance for spin qubit readout operations in monolithic quantum processors. The TIA has been designed and fabricated in a 22nm FDSOI CMOS foundry technology commercially available. The measurement results show a transimpedance gain of 103 dB{\Omega} with a bandwidth of 13 GHz, at room temperature, and it is expected to exhibit slightly superior performance at cryogenic temperatures. The power consumption amounts to 4.1 mW. The core area amount to 0.00025 mm2, i.e., about two orders of magnitude smaller with respect to the prior-art works, and approaching the qubit size, which makes the inductorless TIA a compact enabling solution for monolithic quantum processors.
Transfer of conserved quantities between two remote regions is generally assumed to be a rather trivial process: a flux of particles carrying the conserved quantities propagates from one region to another. We however demonstrate a flow of angular momentum from one region to another across a region of space in which there is a vanishingly small probability of any particles (or fields) being present. This shows that the usual view of how conservation laws work needs to be revisited.
The multiple puns in the title play on a curiosity, that the rescue of a person overboard at sea and the dominance of the second Born term in charge transfer in atomic collisions share common elements of physics. Essentials and commonality in the two are explained.
Expressions for the entropy and equations for the quantum distribution functions in systems of non-interacting fermions and bosons with an arbitrary, including small, number of particles are obtained in the paper
Disorder can have dramatic impact on the transport properties of quantum systems. On the one hand, Anderson localization, arising from destructive quantum interference of multiple-scattering paths, can halt transport entirely. On the other hand, processes involving time-dependent random forces such as Fermi acceleration, proposed as a mechanism for high-energy cosmic particles, can expedite particle transport significantly. The competition of these two effects in time-dependent inhomogeneous or disordered potentials can give rise to interesting dynamics but experimental observations are scarce. Here, we experimentally study the dynamics of an ultracold, non-interacting Fermi gas expanding inside a disorder potential with finite spatial and temporal correlations. Depending on the disorder's strength and rate of change, we observe several distinct regimes of tunable anomalous diffusion, ranging from weak localization and subdiffusion to superdiffusion. Especially for strong disorder, where the expansion shows effects of localization, an intermediate regime is present in which quantum interference appears to counteract acceleration. Our system connects the phenomena of Anderson localization with second-order Fermi acceleration and paves the way to experimentally investigating Fermi acceleration when entering the regime of quantum transport.
The quantum dynamics of vibrational polaritonic states arising from the interaction of a bistable molecule with the quantized mode of a Fabry-Perot microcavity is investigated using an asymmetric double-well potential as a simplified one-dimensional model of a reactive molecule. After discussing the role of the light-matter coupling strength in the emergence of avoided crossings between polaritonic states, we investigate the possibility of using these crossings in order to trigger a dynamical switching of these states from one potential well to the other. Two schemes are proposed to achieve this coherent state switching, either by preparing the molecule in an appropriate vibrational excited state before inserting it into the cavity, or by applying a short laser pulse inside the cavity to obtain a coherent superposition of polaritonic states. The respective influences of the dipole amplitude and potential asymmetry on the coherent switching process are also discussed.
We consider a pair of identical fermions with a short-range attractive interaction on a finite lattice cluster in the presence of strong site disorder. This toy model imitates a low density regime of the strongly disordered Hubbard model. In contrast to spinful fermions, which can simultaneously occupy a site with a minimal energy and thus always form a bound state resistant to disorder, for the identical fermions the probability of pairing on neighboring sites depends on the relation between the interaction and the disorder. The complexity of `brute-force' calculations (both analytical and numerical) of this probability grows rapidly with the number of sites even for the simplest cluster geometry in the form of a closed chain. Remarkably, this problem is related to an old mathematical task of computing the volume of a polyhedron, known as NP-hard. However, we have found that the problem in the chain geometry can be exactly solved by the transfer matrix method. Using this approach we have calculated the pairing probability in the long chain for an arbitrary relation between the interaction and the disorder strengths and completely described the crossover between the regimes of coupled and separated fermions.
The field-free alignment and orientation of the linear molecule by the two-color trapezoidal laser pulses were theoretically investigated. The trapezoidal shape of a laser pulse allows to enhance the maximum alignment degree for the same intensity and duration comparing to the conventional Gaussian laser pulse. The alignment and orientation persist after the pulse for both non-adiabatic and adiabatic regimes. While the maximum (during the pulse) alignment degree quickly saturates and remains almost constant with the pulse duration increase, the dependencies of the maximum (outside the laser pulse) alignment and orientation degrees on the pulse duration show the clear periodic structures in the adiabatic regime. The effect of the non-zero temperature is also shown. Applying additional the monochromatic or two-color prepulse increases the maximum orientation degree, but the application of the two-color prepulse leads to a higher maximum orientation degree than the monochromatic prepulse. The effect of the relative phase variation on the molecular orientation in case of one and two pulses was also discussed.
Scientists have demonstrated that quantum computing has presented novel approaches to address computational challenges, each varying in complexity. Adapting problem-solving strategies is crucial to harness the full potential of quantum computing. Nonetheless, there are defined boundaries to the capabilities of quantum computing. This paper concentrates on aggregating prior research efforts dedicated to solving intricate classical computational problems through quantum computing. The objective is to systematically compile an exhaustive inventory of these solutions and categorize a collection of demanding problems that await further exploration.
Random access codes are a type of communication task that is widely used in quantum information science. The optimal average success probability that can be achieved through classical strategies is known for any random access code. However, only a few cases are solved exactly for quantum random access codes. In this paper, we provide bounds for the fully general setting of n independent variables, each selected from a d-dimensional classical alphabet and encoded in a D-dimensional quantum system subject to an arbitrary quantum measurement. The bound recovers the exactly known special cases, and we demonstrate numerically that even though the bound is not tight overall, it can still yield a good approximation.
We study the polygamy property for tripartite and multipartite quantum systems. In tripartite system, we build a solution set for polygamy in tripartite system and find a lower bound of the set, which can be a sufficient and necessary condition for any quantum entanglement of assistance $Q$ to be polygamous. In multipartite system, we firstly provide generalized definitions for polygamy in two kind of divisions of $n$-qubit systems, and then build polygamy inequalities with a polygamy power $\beta$, repectively. Moreover, we use right triangle and tetrahedron to explain our polygamy relations according to the new definitions.
Quantum key distribution (QKD) could help to share secure key between two distant peers. In recent years, twin-field (TF) QKD has been widely investigated because of its long transmission distance. One of the popular variants of TF QKD is sending-or-not-sending (SNS) QKD, which has been experimentally verified to realize 1000-km level fibre key distribution. In this article, the authors introduce phase postselection into the SNS protocol. With this modification, the probability of selecting "sending" can be substantially improved. The numerical simulation shows that the transmission distance can be improved both with and without the actively odd-parity pairing method. With discrete phase randomization, the variant can have both a larger key rate and a longer distance.
We construct a fault-tolerant quantum error-correcting protocol based on a qubit encoded in a large spin qudit using a spin-cat code, analogous to the continuous variable cat encoding. With this, we can correct the dominant error sources, namely processes that can be expressed as error operators that are linear or quadratic in the components of angular momentum. Such codes tailored to dominant error sources {can} exhibit superior thresholds and lower resource overheads when compared to those designed for unstructured noise models. To preserve the dominant errors during gate operations, we identify a suitable universal gate set. A key component is the CNOT gate that preserves the rank of spherical tensor operators. Categorizing the dominant errors as phase and amplitude errors, we demonstrate how phase errors, analogous to phase-flip errors for qubits, can be effectively corrected. Furthermore, we propose a measurement-free error correction scheme to address amplitude errors without relying on syndrome measurements. Through an in-depth analysis of logical CNOT gate errors, we establish that the fault-tolerant threshold for error correction in the spin-cat encoding surpasses that of standard qubit-based encodings. We consider a specific implementation based on neutral-atom quantum computing, with qudits encoded in the nuclear spin of $^{87}$Sr, and show how to generate the universal gate set, including the rank-preserving CNOT gate, using quantum control and the Rydberg blockade. These findings pave the way for encoding a qubit in a large spin with the potential to achieve fault tolerance, high threshold, and reduced resource overhead in quantum information processing.