arXiv subjects

Lucia A. Popa

Publications and source records attributed to Lucia A. Popa.

3 recordsLinked to original sources

arXiv2025

Gravitational Wave Signatures of Warm Dark Matter in Gauge Extensions of the Standard Model

We study the left-right symmetric extension of the Standard Model (LRSM), featuring a TeV-scale right-handed (RH) gauge boson $W_R$ and three RH neutrinos. This setup naturally realises the type-II seesaw mechanism for active neutrino masses. We identify the conditions that yield sufficient entropy dilution to reconcile the keV sterile neutrino dark matter energy density with observations while inducing an early matter domination (EMD) phase. These constrain the lightest active neutrino mass to 8.59 x 10^{-10} eV < m_{ν_1} < 5.06 x 10^{-9} eV$. The resulting frequency-dependent suppression of the stochastic gravitational wave (GW) background is set by the mass and lifetime of the heavier RH neutrinos. Computing the signal-to-noise ratio (SNR) for future detectors, we find that a blue-tilted primordial tensor spectrum can boost the GW signal to detectable levels (SNR > 10) in experiments such as LISA, BBO, and DECIGO.

hep-ph↗

arXiv2025

Gravitational Waves dynamics with Higgs portal and U(1) X SU(2) interactions

We show that a mixture of Higgs boson with a heavy scalar singlet with large vacuum expectation value ( vev) is a viable model of inflation that satisfy the existing observational data, the perturbativity constraints, avoiding in the same time the EW vacuum metastability as long as the Higgs portal interactions lead to positive tree-level threshold corrections for SM Higgs quartic coupling. The tree-level threshold corrections lead to the change of Hubble expansion rate during inflation with impact on the evolution of the axion-gauge field spectator sector, modifying the time-dependent mass parameter of the gauge field fluctuation. We evaluate this effect on the GW sourced tensor modes while accounting for the consistency and backreaction constraints and show that the Higgs portal interactions enhance the GW signal sourced by the gauge field fluctuations in the CMB B-mode ploarization power spectra. We address the detectability of the GW sourced by the gauge field fluctuations in presence of Higgs portal interactions for the experimental configuration of the future CMB polarization LiteBird space mission. We find that the sourced GW tensor-to-scalar ratio in presence of Higgs portal interactions is enhanced to a level that overcomes the vacuum tensor-to-scalar ratio by a factor of 10, much above the detection threshold of the LiteBird experiment, in agreement with the existing observational constraints on the curvature fluctuations and the allowed parameter space of Higgs portal interactions. We also show that a large enhancement of the sourced GW can be also detected by experiments such as pulsar timing arrays and laser/atomic interferometers. Moreover, a significant Higgs-singlet mixing can be probed by the LHC Higgs searchers.

hep-ph↗

arXiv2019

Cosmological constraints on sterile neutrino Dark Matter production mechanisms

We place constraints on sterile neutrino resonant production (RP) and scalar decay production (SDP) mechanisms assuming that sterile neutrino represents a fraction from the total Cold Dark Matter energy density. For the cosmological analysis, we complement the CMB anisotropies measurements with CMB lensing gravitational potential measurements, that are sensitive to the DM distribution out to high redshifts and with the cosmic shear data, that constraints the gravitational potential at lower redshifts than CMB. We show that our datasets have enough sensitivity to constrain the sterile neutrino mass and mass fraction inside the co-moving free-streaming horizon in both RP and SDP scenarios. For RP case we find that the best fit values of sterile neutrino mass and mixing angle are in the parameter space of interest for sterile neutrino DM decay interpretation of the 3.5 keV X-ray line with a DM mass fraction f_S=0.28 \pm 0.3 (at 68% CL) that excludes the assumption of sterile neutrinos as being all of the DM. For SDP case we find f_S=0.86 \pm 0.07 (at 68% CL), in agreement with the upper limit constraint on f_S from the X-ray non-detection and Ly-alpha forest measurements. The sterile neutrino mass predicted by both RP and SDP models are consistent within 0.3 σ.

astro-ph.CO↗