Flipped heavy neutrinos. From the solar neutrino problem to baryogenesis

Abstract

We discuss baryogenesis using the flipped SU(5) model for lepton mass matrices. We show that the generalized see-saw mechanism in this model cannot only provide MSW neutrino mixing suitable for solving the solar neutrino problem, and supply a hot dark matter candidate ( v τ) with mass O(10)eV as indicated by recent COBE results, but can also naturally account for the baryon asymmetry of the universe. Heavy singlet neutrino decay generates a net lepton asymmetry which is subsequently reprocessed by non-perturbative electroweak interactions. We evaluate the baryon asymmetry so produced in light of the constraints that the COBE observations put on inflationary cosmologies, finding it comfortably consistent with observation.