More Viable Parameter Space for Leptogenesis

Abstract

Lepton flavour asymmetries generated at the onset of the oscillations of sterile neutrinos with masses above the electroweak scale can be large enough to partly survive washout and to explain the baryon asymmetry of the Universe. This opens up new regions of parameter space, where Leptogenesis is viable within the type-I seesaw framework. In particular, we find it possible that the sterile neutrinos masses are substantially below 10^9 GeV, while not being degenerate. However, the required reheat temperature that is determined by the begin of the oscillations lies some orders of magnitude above the sterile neutrino mass-scale.