Flavor and CP symmetries for leptogenesis and 0νββ decay

Abstract

We perform a comprehensive analysis of the phenomenology of leptonic low and high energy CP phases in a scenario with three heavy right-handed neutrinos in which a flavor and a CP symmetry are non-trivially broken. All CP phases as well as lepton mixing angles are determined by the properties of the flavor and CP symmetry and one free real parameter. We focus on the generation of the baryon asymmetry YB of the Universe via unflavored leptogenesis and the predictions of mee, the quantity measurable in neutrinoless double beta decay. We show that the sign of YB can be fixed and the allowed parameter range of mee can be strongly constrained. We argue on general grounds that the CP asymmetries ϵi are dominated by the contribution associated with one Majorana phase and that in cases in which only the Dirac phase is non-trivial the sign of YB depends on further parameters. In addition, we comment on the case of flavored leptogenesis where in general the knowledge of the CP phases and light neutrino mass spectrum is also not sufficient in order to fix the sign of the CP asymmetries. As examples we discuss the series of flavor groups Δ(3n2) and Δ(6n2), n≥2 integer, and several classes of CP transformations.