Leptogenesis in a $\Delta (27)\times SO(10)$ SUSY GUT

Abstract

Although $SO(10)$ Supersymmetric (SUSY) Grand Unification Theories (GUTs) are very attractive for neutrino mass and mixing, it is often quite difficult to achieve successful leptogenesis from the lightest right-handed neutrino $N_1$ due to the strong relations between neutrino and up-type quark Yukawa couplings. We show that in a realistic model these constraints are relaxed, making $N_1$ leptogenesis viable. To illustrate this, we calculate the baryon asymmetry of the Universe $Y_B$ from flavoured $N_1$ leptogenesis in a recently proposed $\Delta (27)\times SO(10)$ SUSY GUT. The flavoured Boltzmann equations are solved numerically, and comparison with the observed $Y_B$ places constraints on the allowed values of right-handed neutrino masses and neutrino Yukawa couplings. The flavoured $SO(10)$ SUSY GUT is not only fairly complete and predictive in the lepton sector, but can also explain the BAU through leptogenesis with natural values in the lepton sector albeit with some tuning in the quark sector.

Comments: v1: 18 pages, 4 figures; v2: 20 pages, 4 figures. Expanded discussion of results, with new figures; v3: 22 pages, 4 figures. Version accepted in JHEP, new fit added