Flavor Leptogenesis During Reheating Era

TL;DR

This paper investigates how the decay of right-handed neutrinos during the reheating era influences flavor leptogenesis, highlighting the impact on equilibration temperatures and the emergence of quasi-thermal leptogenesis.

Contribution

It extends previous analyses by including RHN production from inflaton decay, revealing new effects on energy density distribution and leptogenesis during reheating.

Findings

Decay of the lightest RHN enables flavor leptogenesis during reheating.

Inclusion of inflaton-produced RHNs alters the reheating temperature.

A framework for quasi-thermal leptogenesis is established.

Abstract

Recently, it has been shown that the presence of a non-instantaneous era of reheating can significantly alter the charged lepton(s) equilibration temperature(s) which plays important role in flavor leptogenesis. In this work, we extend the analysis to a more general situation where RHNs are also produced from the decay of the inflaton. The presence of these RHNs along with the thermally generated ones (above its mass equivalent temperature only) redistributes different components of the energy density of the Universe during this reheating era, thereby affecting the charged lepton equilibration temperature (in addition to the Hubble effect) as well as the final reheating temperature $T_{\rm{RH}}$. Taking both the effects into account, we find that the decay of the lightest RHN in the set-up not only provides a platform to study flavor leptogenesis during reheating, but also an interesting framework of $quasi$-thermal leptogenesis emerges.