arXiv subjects

Rajat Kumar Mandal

Publications and source records attributed to Rajat Kumar Mandal.

2 recordsLinked to original sources

arXiv2026

First Order Phase Transition Induced Graviton Bremsstrahlung: A Multi Peak Gravitational Wave Signature

Gravitational waves (GWs) from first order phase transitions (FOPTs) are conventionally sourced by bubble collisions, sound waves, and plasma turbulence. We propose a novel microscopic GW source arising from graviton bremsstrahlung during the decay of the scalar field driving the FOPT. In the presence of Yukawa interactions with light fermions, the scalar decay is inevitably accompanied by graviton emission due to the universal coupling of gravity to the energy-momentum tensor. We show that these gravitons generate an additional stochastic GW background during the phase-transition epoch, complementing the conventional FOPT signal. The resulting GW spectrum can exhibit a characteristic multi-peaked structure. Unlike scenarios in which different GW components originate from distinct cosmological epochs, all contributions considered here emerge from the dynamics of the same FOPT, offering a unique probe of both its microscopic particle dynamics and macroscopic plasma evolution.

hep-ph↗

arXiv2025

Probing Right Handed Neutrino assisted Reheating with Gravitational Waves and Leptogenesis

We investigate a non-instantaneous reheating period in the early Universe, where the inflaton field decays exclusively to right-handed neutrinos (RHNs). The subsequent decay of these RHNs into Standard Model particles not only drives the transition to a radiation-dominated era but also generates the baryon asymmetry of the Universe via leptogenesis. In this typical reheating scenario, gravitational waves (GWs) can be produced during inflaton decay, both through bremsstrahlung and inflaton scattering processes. While GW production via bremsstrahlung dominates near the end of the reheating phase, inflaton scattering leads to a non-negligible GW contribution near the maximum temperature of the Universe. The combined GW spectrum from both decay and scattering processes lies within the sensitivity range of proposed resonant cavity experiments. This framework thus offers a compelling and unified approach to addressing neutrino mass generation, the baryon asymmetry of the Universe via leptogenesis, and probing the dynamics of a non-instantaneous reheating era.

hep-ph↗