Cosmological Implications of Dark Matter Bound States

TL;DR

This paper develops formulas to evaluate how Sommerfeld effects and bound-state formation influence the thermal relic abundance of non-abelian dark matter, impacting mass predictions and indirect detection signals.

Contribution

It introduces generic calculations for bound-state effects on dark matter relic density, including non-abelian gauge interactions and co-annihilation scenarios.

Findings

Bound states increase the required DM mass to 14 TeV for correct relic density.

Predicted gamma-ray line at 85 GeV from bound-state effects.

Bound states significantly affect relic abundance in colored co-annihilation cases.

Abstract

We present generic formulae for computing how Sommerfeld corrections together with bound-state formation affects the thermal abundance of Dark Matter with non-abelian gauge interactions. We consider DM as a fermion 3plet (wino) or 5plet under SU(2)$_L$. In the latter case bound states raise to 14 TeV the DM mass required to reproduce the cosmological DM abundance and give indirect detection signals such as (for this mass) a dominant $\gamma$-line around 85 GeV. Furthermore, we consider DM co-annihilating with a colored particle, such as a squark or a gluino, finding that bound state effects are especially relevant in the latter case.