Implications of an additional scale on leptogenesis

TL;DR

This paper explores how an extra energy scale from a broken $U(1)_X$ symmetry can significantly alter leptogenesis, enabling successful baryogenesis even with zero total CP violation.

Contribution

It introduces a novel scenario where an additional scale allows for successful TeV-scale leptogenesis without requiring CP violation.

Findings

Extra scale can change leptogenesis dynamics

Successful baryogenesis possible with zero CP asymmetry

Boltzmann equations confirm viability of new scenarios

Abstract

We consider variations of the standard leptogenesis picture arising from the presence of an additional scale related to the breaking of a $U(1)_X$ abelian flavor symmetry. We show that quite generically the presence of an additional energy scale might introduce new qualitative and quantitative changes on leptogenesis. Especially interesting is the possibility of having succesful TeV leptogenesis with a vanishing total CP violating asymmetry. By solving the corresponding Boltzmann equations it is shown that these kind of scenarios encounters no difficulties in generating the Cosmic baryon asymmetry.