Baryon asymmetry and flavor symmetry beyond the standard model

Abstract

We have studied various models of baryon asymmetry of the universe and flavor symmetry beyond the standard model. In the study of baryon asymmetry models, we concentrate on the mechanism of leptogenesis, baryon asymmetry through lepton asymmetry. In the first model of baryon asymmetry, CP violation necessary for baryon asymmetry has the same origin with CP violation of neutrino oscillations. We have shown that the observed baryon asymmetry is realizable within the bound of the current neutrino data. Baryogenesis is via resonant leptogenesis, which is free of the gravitino problem. We have also made predictions for the upcoming neutrino experiments. In the other models of baryon asymmetry we have studied some new ways of leptogenesis in the supersymmetry scenario through the decay of the right handed sneutrinos. We have shown that the new ways of leptogenesis are viable to generate the observed baryon asymmetry without inducing the gravitino abundance problem existing in supersymmetry models. In the study of flavor symmetry we have made phenomenological studies of a multi-Higgs model based on the Q6 flavor symmetry. Through fitting experimental data of neutral meson mixing, we have determined the mass spectrum of the heavy Higgs. We then made other phenomenological studies with these Higgs masses. We have found the contributions through heavy Higgs exchange are sufficiently suppressed by flavor symmetry.