Dark CP violation through the Z portal

Despite great agreement with experiment, the Standard Model (SM) of particle physics lacks a viable dark matter (DM) candidate and sufficient amount of CP violation to account for the observed baryon excess in the universe. Nonminimal Higgs frameworks are economic extensions of the SM which could remedy these shortcomings. Within the framework of a three Higgs doublet model, we introduce an extended dark sector which accommodates both DM and CP violation. Such dark sources of CP violation do not contribute to the electric dipole moments and are therefore unconstrained. We present a novel mechanism in which the CP-violating dark particles only interact with the SM through the gauge bosons, primarily the Z boson. Such Z-portal dark CP violation is realized in the regions of the parameter space where Higgs-mediated (co)annihilation processes are subdominant and have negligible contributions to the DM relic density. We show that such Z-portal CP-violating DM can still thermalize and satisfy all experimental and observational bounds and discuss the implications of such phenomena for electroweak baryogenesis.Peer reviewe