Thermal dark matter co-annihilating with a strongly interacting scalar

TL;DR

This paper investigates the impact of soft scatterings and thermal dissociation on bound state formation in thermal dark matter models involving a strongly interacting scalar, extending previous work that only considered gluon radiation effects.

Contribution

It introduces a non-relativistic effective theory approach to include soft 2->2 scatterings and thermal dissociation in dark matter co-annihilation calculations, providing new bounds on mass scales.

Findings

Mass splitting bounds between Majorana and scalar fields.

Dark matter mass scale can reach 5-6 TeV.

Soft scatterings significantly affect bound state dynamics.

Abstract

Recently many investigations have considered Majorana dark matter co-annihilating with bound states formed by a strongly interacting scalar field. However only the gluon radiation contribution to bound state formation and dissociation, which at high temperatures is subleading to soft 2->2 scatterings, has been included. Making use of a non-relativistic effective theory framework and solving a plasma-modified Schrodinger equation, we address the effect of soft 2->2 scatterings as well as the thermal dissociation of bound states. We argue that the mass splitting between the Majorana and scalar field has in general both a lower and an upper bound, and that the dark matter mass scale can be pushed at least up to 5...6 TeV.