WIMPy Leptogenesis With Absorptive Final State Interactions

TL;DR

This paper explores leptogenesis models where dark matter annihilation, involving absorptive final state interactions, generates lepton asymmetry through CP and lepton number violation, highlighting the role of one-loop contributions.

Contribution

It introduces a class of models linking dark matter annihilation with leptogenesis via absorptive final state interactions and clarifies the connection to CP-violating phases.

Findings

One-loop absorptive interactions are crucial for CP violation in these models.

Small branching fractions to leptons can still produce sufficient asymmetry.

The relationship between one-loop effects and CP phases is explicitly elucidated.

Abstract

We consider a class of leptogenesis models in which the lepton asymmetry arises from dark matter annihilation processes which violate CP and lepton number. Importantly, a necessary one-loop contribution to the annihilation matrix element arises from absorptive final state interactions. We elucidate the relationship between this one-loop contribution and the CP-violating phase. As we show, the branching fraction for dark matter annihilation to leptons may be small in these models, while still generating the necessary asymmetry.