On fast CP violating interactions in leptogenesis

TL;DR

This paper demonstrates that in leptogenesis with rapid CP violating interactions, matter asymmetries are governed by a balance condition, revealing new effects of flavor-changing interactions in the strong washout regime.

Contribution

It provides a simplified understanding of leptogenesis dynamics in the strong washout regime and uncovers non-trivial flavor effects relevant for leptogenesis models.

Findings

Matter asymmetries are determined by a balance condition in fast CP violation regimes.

Identifies non-trivial effects of lepton number conserving flavor-changing interactions.

Simplifies the understanding of leptogenesis features in the strong washout regime.

Abstract

We show that when the relevant CP violating interactions in leptogenesis are fast, the different matter density asymmetries are determined at each instant by a balance condition between the amount of asymmetry being created and destroyed. This fact allows to understand in a simple way many features of leptogenesis in the strong washout regime. In particular, we find some non-trivial effects of flavour changing interactions that conserve lepton number, which are specially relevant in models for leptogenesis that rely heavily on flavour effects.