Probing Right Handed Neutrino assisted Reheating with Gravitational Waves and Leptogenesis

TL;DR

This paper explores a non-instantaneous reheating scenario where inflaton decay to right-handed neutrinos drives leptogenesis and generates gravitational waves, which could be detected by future experiments, linking early Universe dynamics with observable signals.

Contribution

It introduces a unified model connecting non-instantaneous reheating, leptogenesis, and gravitational wave production within a right-handed neutrino framework.

Findings

GW spectrum within proposed experimental sensitivity

Reheating dynamics influence GW production mechanisms

Leptogenesis successfully explains baryon asymmetry

Abstract

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.