Flavoured soft leptogenesis and natural values of the B term

TL;DR

This paper explores how relaxing universality assumptions in soft leptogenesis enhances efficiency through flavor effects, allowing successful leptogenesis with TeV-scale B terms and large washout parameters.

Contribution

It demonstrates that hierarchical flavor configurations significantly boost leptogenesis efficiency and that off-diagonal soft slepton masses do not suppress these effects.

Findings

Hierarchical flavor configurations increase efficiency by over two orders of magnitude.

Soft leptogenesis can succeed with B~TeV and large washout parameters.

Lepton flavor equilibration effects are ineffective at damping enhancements.

Abstract

We revisit flavour effects in soft leptogenesis relaxing the assumption of universality for the soft supersymmetry breaking terms. We find that with respect to the case in which the heavy sneutrinos decay with equal rates and equal CP asymmetries for all lepton flavours, hierarchical flavour configurations can enhance the efficiency by more than two orders of magnitude. This translates in more than three order of magnitude with respect to the one-flavour approximation. We verify that lepton flavour equilibration effects related to off-diagonal soft slepton masses are ineffective for damping these large enhancements. We show that soft leptogenesis can be successful for unusual values of the relevant parameters, allowing for $B\sim {\cal O}({\rm TeV})$ and for values of the washout parameter up to $m_{\rm eff}/m_* \sim 5\times 10^{3}$.