Annihilating Asymmetric Dark Matter

TL;DR

This paper investigates the relic abundance and annihilation processes of asymmetric dark matter, deriving constraints from cosmic microwave background and gamma-ray data, and analyzing gamma-ray emissions from the Galactic Center.

Contribution

It introduces a method to determine the annihilation cross section in asymmetric dark matter models considering primordial asymmetry effects.

Findings

Anti-DM number density is 1-4% of DM for tau lepton channels.

Anti-DM can be 50-100% of DM for b-quark channels.

Constraints are derived from CMB and Fermi-LAT gamma-ray observations.

Abstract

The relic abundance of particle and antiparticle dark matter (DM) need not be vastly different in thermal asymmetric dark matter (ADM) models. By considering the effect of a primordial asymmetry on the thermal Boltzmann evolution of coupled DM and anti-DM, we derive the requisite annihilation cross section. This is used in conjunction with CMB and Fermi-LAT gamma-ray data to impose a limit on the number density of anti-DM particles surviving thermal freeze-out. When the extended gamma-ray emission from the Galactic Center is reanalyzed in a thermal ADM framework, we find that annihilation into $\tau$ leptons prefer anti-DM number densities 1-4$\%$ that of DM while the $b$-quark channel prefers 50-100$\%$.