Leptogenesis enabled by dark matter

Abstract

We propose that weak scale leptogenesis via ∼10TeV scale right-handed neutrinos could be possible if their couplings had transitory larger values in the early Universe. The requisite lifted parameters can be attained if a light scalar ϕ is displaced a long distance from its origin by the thermal population of fermions X that become massive before electroweak symmetry breaking. The fermion X can be a viable dark matter candidate; for suitable choice of parameters, the light scalar itself can be dark matter through a misalignment mechanism. We find that a two-component dark matter population made up of both X and ϕ is a typical outcome in our framework.