Abstract: We investigate a consistent scenario of time-varying neutrino masses, and discuss its impact on cosmology, beta decay, and neutrino oscillation experiments. Such time-varying masses are assumed to be generated by the coupling between a sterile neutrino and an ultralight scalar field, which in turn affects the light neutrinos by mixing. We demonstrate how various cosmological bounds, such as those coming from big bang nucleosynthesis, the cosmic microwave background, as well as large scale structures, can be evaded in this model. This scenario can be further constrained using multiple terrestrial experiments. In particular, for beta-decay experiments like KATRIN, nontrivial distortions to the electron spectrum can be induced, even when time-variation is fast and it gets averaged. Furthermore, the presence of time-varying masses of sterile neutrinos will alter the interpretation of light sterile neutrino parameter space in the context of the reactor and gallium anomalies. In addition, we also study the impact of such time-varying neutrino masses on results from the BEST collaboration, which have recently strengthened the gallium anomaly. If confirmed, we find that the time-varying neutrino mass hypothesis could give a better fit to the recent BEST data.

Abstract: A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139 fb(-1) of proton-proton collision data at root s=13 TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into (tt) over bar in the ATLAS muon spectrometer.

Abstract: Ground and isomeric states of the neutron-deficient odd-A isotopes 183Hg, 185Hg, and 187Hg are described from a microscopic calculation based on a self-consistent, axially deformed Hartree-Fock mean field with the Skyrme functional and pairing within BCS approximation. For each equilibrium shape and different odd-neutron states, results on mean-square charge radii and magnetic dipole moments are given and analyzed in the context of their sensitivity to the nuclear deformation and to the spin and parity. Spin-isospin correlations within proton-neutron quasiparticle random phase approximation are then introduced in the nuclear states to obtain the distributions of Gamow-Teller strength and the beta+/EC half-lives of these isotopes, whose measurements are planned at ISOLDE-CERN using total absorption gamma-ray spectroscopy techniques.

Abstract: We present robust, model-marginalized limits on both the total neutrino mass (E m1,) and abundances (Neff) to minimize the role of parametrizations, priors and models when extracting neutrino properties from cosmology. The cosmological observations we consider are cosmic microwave background temperature fluctuation and polarization measurements, supernovae Ia luminosity distances, baryon acoustic oscillation observations and determinations of the growth rate parameter from the Data Release 16 of the Sloan Digital Sky Survey IV. The degenerate neutrino mass spectrum (which implies the prior sigma m(1), > 0) is weakly or moderately preferred over the normal and inverted hierarchy possibilities, which imply the priors sigma m(1), > 0.06 and sigma m(1), > 0.1 eV respectively. Concerning the underlying cosmological model, the ACDM minimal scenario is almost always strongly preferred over the possible extensions explored here. The most constraining 95% CL bound on the total neutrino mass in the ACDM + sigma m(1), picture is sigma m(1), < 0.087 eV. The parameter N-eff is restricted to 3.08 +/- 0.17 (68% CL) in the ACDM + Neff model. These limits barely change when considering the ACDM + sigma m(1), + Neff scenario. Given the robustness and the strong constraining power of the cosmological measurements employed here, the model -marginalized posteriors obtained considering a large spectra of nonminimal cosmologies are very close to the previous bounds, obtained within the ACDM framework in the degenerate neutrino mass spectrum. Future cosmological measurements may improve the current Bayesian evidence favoring the degenerate neutrino mass spectra, challenging therefore the consistency between cosmological neutrino mass bounds and oscillation neutrino measurements, and potentially suggesting a more complicated cosmological model and/or neutrino sector.

Abstract: We extend the method of adiabatic regularization by introducing an arbitrary parameter μfor a scalar field with quartic self-coupling in a Friedmann-Lemaitre-Robertson-Walker spacetime at one-loop order. The subtraction terms constructed from this extended version allow us to define a preferred vacuum state at a fixed time ri 1/4 ri0 for this theory. We compute this vacuum state for two commonly used background fields in cosmology, specially in the context of preheating. We also give a possible prescription for an adequate value for mu.