Radiative bound-state-formation cross-sections for dark matter interacting via a Yukawa potential

TL;DR

This paper computes the cross-sections for radiative formation of dark matter bound states via a Yukawa potential, crucial for understanding dark matter interactions in cosmology and particle physics.

Contribution

It provides the leading-order calculations for bound-state formation cross-sections involving vector or scalar emission, including velocity dependence and resonance effects.

Findings

Cross-sections depend on velocity and potential parameters.

Resonance structures significantly enhance formation rates.

Comparison with annihilation processes highlights their relative importance.

Abstract

We calculate the cross-sections for the radiative formation of bound states by dark matter whose interactions are described in the non-relativistic regime by a Yukawa potential. These cross-sections are important for cosmological and phenomenological studies of dark matter with long-range interactions, residing in a hidden sector, as well as for TeV-scale WIMP dark matter. We provide the leading-order contributions to the cross-sections for the dominant capture processes occurring via emission of a vector or a scalar boson. We offer a detailed inspection of their features, including their velocity dependence within and outside the Coulomb regime, and their resonance structure. For pairs of annihilating particles, we compare bound-state formation with annihilation.