Implementing asymmetric dark matter and dark electroweak baryogenesis in a mirror two-Higgs-doublet model

Abstract

Models of asymmetric dark matter (ADM) seek to explain the apparent coincidence between the present-day mass densities of visible and dark matter, ΩDM 5ΩVM. However, most ADM models only relate the number densities of visible and dark matter without motivating the similar particle masses. We expand upon a recent work that obtained a natural mass relationship in a mirror matter ADM model with two Higgs doublets in each sector, by looking to implement dark electroweak baryogenesis as the means of asymmetry generation. We explore two aspects of the mechanism: the nature of the dark electroweak phase transition, and the transfer of particle asymmetries between the sectors by the use of portal interactions. We find that both aspects can be implemented successfully for various regions of the parameter space. We also analyse one portal interaction – the neutron portal – in greater detail, in order to satisfy the observational constraints on dark radiation.