Opening a new window for warm dark matter

摘要

We explore the range of parameters for dark-matter sterile neutrinos in anextention of the Minimal Standard Model by three singlet fermions with massesbelow the electroweak scale (the $\nu$MSM). This simple model can explain awide range of phenomena, including neutrino oscillations, baryogenesis, thepulsar velocities, and the early reionization. The presence of two heaviersterile neutrinos and the possibility of entropy production in their decaysbroadens the allowed range of parameters for the dark-matter sterile neutrinos(or other types of dark matter, for example, the gravitino). In addition, theprimordial production of dark matter sterile neutrinos allows to escape most ofthe constraints.