Revisiting Big-Bang Nucleosynthesis Constraints on Dark-Matter Annihilation

TL;DR

This paper investigates how dark-matter annihilation during big-bang nucleosynthesis affects light-element abundances, improving calculations by including anti-nucleon effects and neutron-proton interconversions, to set new constraints on dark matter models.

Contribution

It introduces an improved calculation method for primordial abundances considering anti-nucleons and neutron-proton interconversions, refining constraints on dark-matter annihilation cross sections.

Findings

Derived upper bounds on dark-matter annihilation cross sections.

Enhanced accuracy in primordial abundance predictions.

Implications for particle-physics dark matter models.

Abstract

We study the effects of dark-matter annihilation during the epoch of big-bang nucleosynthesis on the primordial abundances of light elements. We improve the calculation of the light-element abundances by taking into account the effects of anti-nucleons emitted by the annihilation of dark matter and the interconversion reactions of neutron and proton at inelastic scatterings of energetic nucleons. Comparing the theoretical prediction of the primordial light-element abundances with the latest observational constraints, we derive upper bounds on the dark-matter pair-annihilation cross section. Implication to some of particle-physics models are also discussed.