Asymmetric dark matter in extended exo-Higgs scenarios

Abstract

The exo-Higgs model can accommodate a successful baryogenesis mechanism that closely mirrors electroweak baryogenesis in the Standard Model, but avoids its shortcomings. We extend the exo-Higgs model by the addition of a singlet complex scalar χ. In our model, χ can be a viable asymmetric dark matter (ADM) candidate. We predict the mass of the ADM particle to be mχ≈1.3 GeV. The leptophilic couplings of χ can provide for efficient annihilation of the ADM pairs. We also discuss the LHC signals of our scenario, and in particular the production and decays of exo-leptons which would lead to “lepton pair plus missing energy” final states. Our model typically predicts potentially detectable gravitational waves originating from the assumed strong first order phase transition at a temperature of ∼ TeV. If the model is further extended to include new heavy vector-like fermions, e.g. from an ultraviolet extension, χ couplings could explain the ∼3.5σ muon g−2 anomaly.