The reheating era leptogenesis in models with seesaw mechanism

TL;DR

This paper investigates how leptogenesis during the reheating era can be explained within seesaw models, highlighting the role of higher dimensional operators and CP violation in generating baryon asymmetry.

Contribution

It demonstrates that reheating era leptogenesis can originate from higher dimensional operators in seesaw models, providing a new perspective on baryogenesis without specifying high-energy physics.

Findings

Effective CP-violating interactions are present in several seesaw models.

Reheating era leptogenesis is viable within these models.

Possibility of lowering reheating temperature in radiative seesaw models.

Abstract

Observed baryon asymmetry can be achieved not only by the decay of right-handed neutrinos but also by the scattering processes in the reheating era. In the latter scenario, new physics in high energy scale does not need to be specified, but only two types of the higher dimensional operator of the standard model particles are assumed in the previous work. In this paper, we examine the origin of the higher dimensional operators assuming models with a certain seesaw mechanism at the high energy scale. The seesaw mechanism seems to be a simple realization of the reheating era leptogenesis because the lepton number violating interaction is included. We show that the effective interaction giving CP violating phases is provided in the several types of models and also the reheating era leptogenesis actually works in such models. Additionally, we discuss a possibility for lowering the reheating temperature in the radiative seesaw models, where the large Yukawa coupling is naturally realized.