Asymmetric Dark Matter From Scattering

Abstract

In dark matter (DM) cosmology, the central question is how the present-day density of DM is generated from some initial conditions in the early universe. Different production mechanisms of DM are instrumental in probing DM microphysics in current and future experiments and observations. In this context, thermal dark matter is historically most-studied scenario, in which DM is thermalized with the visible sector in the early universe. Thermalized DM sector is described by visible sector temperature and a chemical potential in general. In particular, a non-zero chemical potential of DM indicates a difference (asymmetry) between particle-antiparticle number densities in the dark sector. In this work, we have studied the generation of DM chemical potential only from DM scatterings and their interplay in the early universe, consequently its effect on the present-day density and the composition of DM.