Leptogenesis-Maki-Nakagawa-Sakata link in unified models with natural neutrino mass hierarchy

We discuss the relation between leptogenesis and the Maki-Nakagawa-Sakata (MNS) phases in the class of seesaw models called light sequential dominance in which the right-handed neutrinos dominate sequentially, with the dominant right-handed neutrino being the lightest one. The heaviest right-handed neutrino then decouples, leaving effectively two right-handed neutrinos. Light sequential dominance is motivated by SO(10) models which predict three right-handed neutrinos. With an approximate Yukawa texture zero in the 11 position there are only two seesaw phases which are simply related to the MNS phase measurable at a neutrino factory and the leptogenesis phase. The leptogenesis phase is predicted to be equal to the neutrinoless double beta decay phase.