Aditi Krishak, Shantanu Desai

We perform an independent search for annual modulation in the recently released COSINE-100 data, which could be induced by dark matter scatterings. We test the hypothesis that the data contains a sinusoidal modulation against the null hypothesis, that the data consists of only background. We compare the significance using frequentist method, information theoretic techniques (such as AIC and BIC), and finally a Bayesian model comparison technique. Both the frequentist and Bayesian techniques reveal no significant differences between the two hypotheses, whereas the null hypothesis is slightly favored according to AIC and BIC-based tests. This is the first proof of principles demonstration of application of Bayesian and information theory based techniques to COSINE-100 data to assess the significance of annual modulation.

Matthew R. Gomer, Liliya L. R. Williams

Gravitational lensing offers a a competitive method to measure $H_0$ with the goal of 1% precision. A major obstacle comes in the form of lensing degeneracies, such as the mass sheet degeneracy (MSD), which make it possible for a family of density profiles to reproduce the same lensing observables but return different values of $H_0$. The modeling process artificially selects one choice from this family, potentially biasing the recovered value of $H_0$. The effect is more pronounced when the profile of a given lens is not perfectly described by the lens model, which will always be the case to some extent. To explore this, we quantify the bias and spread by creating quads from two-component mass models and fitting them with a power-law ellipse+shear model. We find that the bias does not correspond to the estimate one would calculate by transforming the profile into a power law near the image radius. We also emulate the effect of including stellar kinematics by performing fits where the slope is constrained to the true value over a range of radii. Constraining the slope to the true value near the image radius can introduce substantial bias (0-8% for our most realistic models). We conclude that lensing degeneracies manifest in a more complicated way than is assumed. If stellar kinematics incorrectly break the MSD, their inclusion may introduce more bias than their omission.

Ziwei Wang, Robert Brandenberger, Lavinia Heisenberg

It has been suggested that low energy effective field theories should satisfy given conditions in order to be successfully embedded into string theory. In the case of a single canonically normalized scalar field this translates into conditions on its potential and the derivatives thereof. In this Letter we revisit stochastic models of small field inflation and study the compatibility of the swampland constraints with entropy considerations. We show that stochastic inflation either violates entropy bounds or the swampland criterium on the slope of the scalar field potential. Furthermore, we illustrate that such models are faced with a graceful exit problem: any patch of space which exits the region of eternal inflation is either not large enough to explain the isotropy of the cosmic microwave background, or has a spectrum of fluctuations with an unacceptably large red tilt.

Carlos A. Argüelles, Mauricio Bustamante, Ali Kheirandish, Madison), Sergio Palomares-Ruiz, IFIC), Jordi Salvado, ECM & ICC, Barcelona U.), Aaron C. Vincent, Kingston & Perimeter Inst. Theor. Phys.)

The astrophysical neutrinos discovered by IceCube have the highest detected neutrino energies --- from TeV to PeV --- and likely travel the longest distances --- up to a few Gpc, the size of the observable Universe. These features make them naturally attractive probes of fundamental particle-physics properties, possibly tiny in size, at energy scales unreachable by any other means. The decades before the IceCube discovery saw many proposals of particle-physics studies in this direction. Today, those proposals have become a reality, in spite of astrophysical unknowns. We will showcase examples of doing fundamental neutrino physics at these scales, including some of the most stringent tests of physics beyond the Standard Model. In the future, larger neutrino energies --- up to tens of EeV --- could be observed with larger detectors and further our reach.

Yan Liu, Jing-Fei Zhang, Xin Zhang

In this work, we investigate what extent the cosmological parameters can be constrained to when the redshift drift data of Square Kilometre Array (SKA) are used alone and what will happen when the European Extremely Large Telescope (E-ELT) and SKA mock data are combined. The $\Lambda$CDM model is chosen as a reference model to reach our aims. We find that using the SKA1-only mock data, the $\Lambda$CDM model can be loosely constrained, while the model can be well constrained when the SKA2-only mock data are used. When the combination of SKA and E-ELT mock data are considered, the constraints can be significantly improved almost as good as the data combination of the type Ia supernovae observation, the cosmic microwave background observation, and the baryon acoustic oscillations observation. Furthermore, we also investigate in the future what role the redshift drift data of SKA will play in the cosmological parameter estimation. We use four dark energy models, namely, the $\Lambda$CDM model, the $w$CDM model, the CPL model, and the HDE model, as examples to make the analysis. These models are favored by the current observations well. we find that the redshift drift measurement of SKA could help to significantly improve the constraint on dark energy and could break the degeneracy existing between the cosmological parameters. Therefore, we conclude that redshift-drift observation of SKA would provide a good improvement in the cosmological parameter estimation in the future and have the enormous potential to be one of the most competitive cosmological probes in constraining dark energy.