Renormalisation group improved leptogenesis in family symmetry models

TL;DR

This paper investigates how renormalisation group corrections can enable leptogenesis in family symmetry models where CP violation is initially suppressed, showing that RG effects are crucial for viable leptogenesis.

Contribution

It demonstrates that RG corrections break form dominance in family symmetry models, allowing for successful leptogenesis where it was previously suppressed at the symmetry breaking scale.

Findings

RG corrections violate form dominance in family symmetry models.

RG effects enable viable leptogenesis at the right-handed neutrino mass scale.

RG corrections are essential in models with sizeable neutrino and tau Yukawa couplings.

Abstract

We study renormalisation group (RG) corrections relevant for leptogenesis in the case of family symmetry models such as the Altarelli-Feruglio A4 model of tri-bimaximal lepton mixing or its extension to tri-maximal mixing. Such corrections are particularly relevant since in large classes of family symmetry models, to leading order, the CP violating parameters of leptogenesis would be identically zero at the family symmetry breaking scale, due to the form dominance property. We find that RG corrections violate form dominance and enable such models to yield viable leptogenesis at the scale of right-handed neutrino masses. More generally, the results of this paper show that RG corrections to leptogenesis cannot be ignored for any family symmetry model involving sizeable neutrino and tau Yukawa couplings.