The number density of a charged relic

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 the 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 an 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. © 2008 IOP Publishing Ltd.