Dark matter, singlet extensions of the nuMSM, and symmetries

Understand

We consider an extension of the nuMSM in which sterile neutrino masses originate from the VEV of a Higgs singlet phi and dark matter is produced through the decays of phi rather than through active-sterile neutrino mixing.

• This model, which we refer to as the nuNMSM, can readily satisfy or escape the constraints on warm dark matter from the Lyman-alpha forest and other small scale structure.
• However, it requires a particular hierarchy of Majorana masses and Yukawa couplings without an obvious origin.
• We show that the hierarchical parameters of the nuNMSM can arise from symmetries broken at or near the Planck scale for two specific examples of this model: one in which phi helps stabilize the electroweak vacuum through a scalar threshold effect and one in which phi is a light inflaton.