New Ways to Leptogenesis with Gauged B-L Symmetry

Abstract

We show that in supersymmetric models with gauged B-L symmetry, there is a new source for cosmological lepton asymmetry. The Higgs bosons responsible for B-L gauge symmetry breaking decay dominantly into right-handed sneutrinos \tilde{N} and \tilde{N}* producing an asymmetry in \tilde{N} over \tilde{N}*. This can be fully converted into ordinary lepton asymmetry in the decays of \tilde{N}. In simple models with gauged B-L symmetry we show that resonant/soft leptogenesis is naturally realized. Supersymmetry guarantees quasi-degenerate scalar states, while soft breaking of SUSY provides the needed CP violation. Acceptable values of baryon asymmetry are obtained without causing serious problems with gravitino abundance.

14 pp, LaTeX, 2 eps figures, typos fixed