Radiative corrections to co-annihilation processes

TL;DR

This paper investigates the impact of radiative QCD corrections on co-annihilation processes in dark matter models, specifically analyzing neutralino-stop co-annihilation in supersymmetry, revealing significant effects on the annihilation cross-section.

Contribution

It provides the first detailed calculation of leading QCD radiative corrections to neutralino-stop co-annihilation in supersymmetry, showing their large influence on the effective annihilation rate.

Findings

QCD corrections can alter the annihilation cross-section by over 50%.

Radiative corrections significantly impact dark matter relic density calculations.

Abstract

In co-annihilation scenarios, the weakly interacting dark matter particle (WIMP) is close in mass to another particle that can decay into the WIMP. As a result, both particles freeze out at roughly the same time in the early universe, and both contribute to the effective dark matter annihilation cross-section. Since the heavier particle does not need to be weakly interacting, the co-annihilation processes are in general subject to sizeable radiative corrections. Here this is analyzed for the example of neutralino-stop co-annihilation in supersymmetry. The leading QCD corrections are calculated and it is found that they have a large effect on the effective annihilation cross-section, reaching more than 50% in some regions of parameter space.