Gravitationally Induced Dark Matter Asymmetry and Dark Nucleon Decay

Abstract

The "gravitational baryogenesis" scenario is extended to generate both baryon and dark matter asymmetries, in the matter dominated era corresponding to post-inflationary reheating. A minimal extension requires a singlet fermion X for dark matter and a singlet scalar S. With two or more hidden sector fermions, the scenario can lead to nucleon decay into dark matter with a lifetime of order 10^{34-36} yr, which is relevant for current or future experiments. The correct multi-component relic density can be obtained if dark matter fermions couple to a sub-GeV vector boson that weakly interacts with the Standard Model through mixing. The typical inflationary scale in the scenario is of order 10^{16} GeV which suggests that tensor mode perturbations could potentially be within observational reach.