The number density of a charged relic

TL;DR

This paper calculates the relic abundance of charged, long-lived scalar particles in the early universe, considering various interactions and effects, and compares these to experimental bounds to constrain supersymmetric models.

Contribution

It provides detailed computations of the relic number density including Sommerfeld enhancement and unitarity limits for charged scalars in cosmology.

Findings

Relic densities vary with interaction type and velocity effects.

Sommerfeld enhancement significantly affects freeze-out abundances.

Results constrain supersymmetric models with charged NLSPs.

Abstract

We investigate scenarios in which a charged, long-lived scalar particle decouples from the primordial plasma in the Early Universe. We compute the number density at time of freeze-out considering both the cases of abelian and non-abelian interactions and including the effect of Sommerfeld enhancement at low initial velocity. We also discuss as extreme case the maximal cross section that fulfils the unitarity bound. We then compare these number densities to the exotic nuclei searches for stable relics and to the BBN bounds on unstable relics and draw conclusions for the cases of a stau or stop NLSP in supersymmetric models with a gravitino or axino LSP.