Lepton Number-Driven Sterile Neutrino Production in the Early Universe

摘要

We examine medium-enhanced, neutrino scattering-induced decoherent productionof dark matter candidate sterile neutrinos in the early universe. In cases witha significant net lepton number we find two resonances, where the effectivein-medium mixing angles are large. We calculate the lepton numberdepletion-driven evolution of these resonances. We describe the dependence ofthis evolution on lepton numbers, sterile neutrino rest mass, and theactive-sterile vacuum mixing angle. We find that this resonance evolution canresult in relic sterile neutrino energy spectra with a generic form which issharply peaked in energy. We compare our complete quantum kinetic equationtreatment with the widely-used quantum Zeno ansatz.