Phenomenological consequences of the seesaw mechanism in S-4 based models

Abstract

Reference [1] proposed a flavor model based on the symmetry group S-4, managing to describe fermion masses and mixings. The Weinberg operator has been used in order to provide the smallness of the neutrino masses, while a set of scalar fields, getting nonvanishing vacuum expectation values, spontaneously breaks down S-4 and provides the tri-bimaximal pattern as the lepton mixing matrix. Restricting to this setting, in this paper we analyze possible origins for the effective terms: the type I seesaw mechanism is the best known approach, but type II and III are also discussed. The phenomenology related to these models is various and future experiments could in principle discriminate among these proposals. Furthermore, we compare our realizations to two relevant A(4) based models, also predicting the tri-bimaximal lepton mixing, and we find that an analysis of the 0 nu 2 beta-decay parameters could distinguish among all these realizations. The introduction of new physics beyond the standard model, like heavy right-handed neutrinos, scalar triplets, and fermion triplets, let us investigate leptogenesis, and this provides constraints in the realization of the models.