Squeezing out predictions with leptogenesis from SO(10)

Abstract

We consider the see-saw mechanism within a nonsupersymmetric SO(10) model. By assuming the SO(10) quark-lepton symmetry, and after imposing suitable conditions that ensure that the right-handed neutrino masses are at most mildly hierarchical (compact right-handed spectrum) we obtain a surprisingly predictive scenario. The absolute neutrino mass scale, the Dirac and the two Majorana phases of the neutrino mixing matrix remain determined in terms of the set of already measured low energy observables, modulo a discrete ambiguity in the signs of two neutrino mixing angles and of the Dirac phase. The right-handed neutrino mass spectrum is also predicted, as well as the size and sign of the leptogenesis $CP$ asymmetries. We compute the cosmological baryon asymmetry generated through leptogenesis and obtain the correct sign, and a size compatible with observations.