WIMP abundance and lepton (flavour) asymmetry

TL;DR

This paper explores how significant lepton asymmetries in the early universe can reduce the relic density of WIMP dark matter, with effects up to 20% for certain asymmetries.

Contribution

It provides a detailed analysis of the impact of large lepton flavour asymmetries on WIMP relic abundance, extending standard calculations.

Findings

Lepton asymmetries can decrease WIMP relic density by up to 20%.

Large lepton flavour asymmetries influence early universe evolution.

The effect depends on the magnitude of the lepton flavour asymmetry.

Abstract

We investigate how large lepton asymmetries affect the evolution of the early universe at times before big bang nucleosynthesis and in particular how they influence the relic density of WIMP dark matter. In comparison to the standard calculation of the relic WIMP abundance we find a decrease, depending on the lepton flavour asymmetry. We find an effect of up to 20 per cent for lepton flavour asymmetries $l_f= {\cal O}(0.1)$.