Gravitational waves from neutrino mass and dark matter genesis

Abstract

We introduce a model in which the genesis of dark matter (DM) and neutrino masses is associated with a first-order phase transition of a scalar singlet field. During the phase transition a source right-handed neutrino (RHN) acquires a spacetime-dependent mass dynamically, a small fraction of which is converted via resonant oscillations into a very weakly mixed dark RHN which decays to a dark matter RHN with the observed relic abundance. Neutrino masses are generated via a traditional two RHN type-I seesaw between a fourth RHN and the source neutrino. The gravitational waves produced during the phase transition have a peak frequency that increases with the DM mass, and are detectable at future gravitational-wave interferometers for DM masses above ∼1 MeV. Since the source RHNs are heavier than the electroweak scale, successful leptogenesis is also attainable.