1 research outputs found
Sterile neutrino dark matter as a consequence of nuMSM-induced lepton asymmetry
It has been pointed out in ref.[1] that in the nuMSM (Standard Model extended
by three right-handed neutrinos with masses smaller than the electroweak
scale), there is a corner in the parameter space where CP-violating resonant
oscillations among the two heaviest right-handed neutrinos continue to operate
below the freeze-out temperature of sphaleron transitions, leading to a lepton
asymmetry which is considerably larger than the baryon asymmetry. Consequently,
the lightest right-handed (``sterile'') neutrinos, which may serve as dark
matter, are generated through an efficient resonant mechanism proposed by Shi
and Fuller [2]. We re-compute the dark matter relic density and non-equilibrium
momentum distribution function in this situation with quantum field theoretic
methods and, confronting the results with existing astrophysical data, derive
bounds on the properties of the lightest right-handed neutrinos. Our spectra
can be used as an input for structure formation simulations in warm dark matter
cosmologies, for a Lyman-alpha analysis of the dark matter distribution on
small scales, and for studying the properties of haloes of dwarf spheroidal
galaxies.Comment: 25 pages. v2: many clarifications and references added; published
versio