Precision calculations of dark matter relic abundance

TL;DR

This paper introduces a momentum-dependent framework for accurately calculating dark matter relic abundance near resonance features, improving upon traditional momentum-averaged methods especially in models with specific interaction strengths.

Contribution

The authors develop an accessible momentum-dependent approach for precise dark matter abundance calculations near resonances, validated in a singlet scalar dark matter model.

Findings

Momentum-dependent method improves accuracy near resonances.

Standard momentum-averaged methods are valid within 20% for certain models.

Updated allowed mass range for light singlet scalar dark matter is 56-62.5 GeV.

Abstract

The dark matter annihilation channels sometimes involve sharp resonances. In such cases the usual momentum averaged approximations for computing the DM abundance may not be accurate. We develop an easily accessible momentum dependent framework for computing the DM abundance accurately and efficiently near such features. We apply the method to the case of a singlet scalar dark matter $s$ interacting with SM through higgs portal $\lambda_{\rm hs}s^2 h^2$ and compare the results with different momentum averaged methods. The accuracy of the latter depend strongly on the strength of the elastic interactions and corrections are large if WIMP has negligible interactions beyond the main annihilation channel. In the singlet scalar model however, the standard model scatterings induce an efficient kinetic equilibrium that validates the momentum averaged computation to 20 per cent accuracy. We update the current extent of the allowed region in the light singlet scalar dark matter to $m_{\rm S} \in [56,62.5]$ GeV.