Triplet Leptogenesis in Left-Right Symmetric Seesaw Models

TL;DR

This paper explores scalar triplet leptogenesis within a left-right symmetric seesaw model, demonstrating how Majorana phases can optimize CP asymmetry and analyzing the conditions for effective leptogenesis.

Contribution

It introduces a detailed analysis of triplet leptogenesis in a specific left-right symmetric model, highlighting the role of Majorana phases and decay branching ratios.

Findings

Majorana phases can saturate CP asymmetry limits

Maximal leptogenesis efficiency occurs with moderate decay branching ratios

Hierarchies in decay channels reduce CP asymmetry effectiveness

Abstract

We discuss scalar triplet leptogenesis in a specific left-right symmetric seesaw model. We show that the Majorana phases that are present in the model can be effectively used to saturate the existing upper limit on the CP-asymmetry of the triplets. We solve the relevant Boltzmann equations and analyze the viability of triplet leptogenesis. It is known for this kind of scenario that the efficiency of leptogenesis is maximal if there exists a hierarchy between the branching ratios of the triplet decays into leptons and Higgs particles. We show that triplet leptogenesis typically favors branching ratios with not too strong hierarchies, since maximal efficiency can only be obtained at the expense of suppressed CP-asymmetries.