UV Leptogenesis

Models of freeze-in dark matter (DM) allow for the generation of the observed matter-antimatter asymmetry through the production, oscillation, and annihilation of DM particles. In contrast with earlier studies which have focused on IR-driven DM production, we perform the first study of leptogenesis via UV freeze-in. We consider two DM candidates χ1, χ2 of different masses: DM production occurs via freeze-in from the scattering of SM particles with a heavy virtual mediator. We do this by deriving and implementing reaction rates into quantum kinetic equations that describe the evolution of the lepton asymmetry, and abundance and quantum state of DM. We use an iterative approach to obtain approximate solutions to the QKEs far from equilibrium, finding that viable parameters exist that simultaneously account for the observed asymmetry and DM abundance. Our calculated reaction densities can be used to develop fully self-consistent treatment of the QKEs close to equilibrium, using the proper quantum statistical distribution functions and accounting for the case where pre-existing asymmetries and DM abundances are large enough to have an effect on the subsequent evolution of the asymmetry.