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

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.