The number density of a charged relic

Understand

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.