Constraints on Asymmetric Dark Matter Self Annihilation Cross Sections in Non-standard Cosmological Scenarios

TL;DR

This paper examines how non-standard cosmological models like kination and brane world scenarios affect the relic abundance and self-annihilation constraints of asymmetric dark matter, revealing that enhanced expansion rates allow larger cross sections and alter mass bounds.

Contribution

It provides new constraints on dark matter self-annihilation cross sections in non-standard cosmologies, highlighting the impact of increased expansion rates on relic abundance and asymmetry preservation.

Findings

Larger self annihilation cross sections are permitted in kination and brane world models.

Enhanced expansion rates cause earlier freeze-out, affecting wash-out of asymmetry.

Lower bounds on sneutrino dark matter mass are reduced compared to standard cosmology.

Abstract

We investigate the relic abundance of asymmetric dark matter in the non-standard cosmological scenarios when the annihilation cross section includes self annihilations. Here we discuss the kination model and brane world cosmology. When the self annihilation is permitted for asymmetric dark matter, there is possibility of washing out the pre-existed asymmetry. We find the constraints on the cross section to avoid the complete washing out of the asymmetry in the non-standard cosmological scenarios. The enhanced cosmic expansion rate causes the freeze out point of wash-out to be earlier. The larger self annihilation cross sections are allowed to exist in kination model and brane world cosmology. Then, in the case of left-handed sneutrino asymmetric dark matter, we find the value of the lower bound on winos mass is smaller than that in the standard cosmological scenario.