Non-vanishing Ue3 under S-3 symmetry

Abstract

This work proposes two models of neutrino masses that predict non-zero theta(13) under the non-Abelian discrete flavor symmetry S-3 circle times Z(2). We advocate that the size of theta(13) is understood as a group theoretical consequence rather than a perturbed effect from the tri-bi-maximal mixing. So, the difference of two models is designed only in terms of the flavor symmetry, by changing the charge assignment of right-handed neutrinos. The PMNS matrix in the first model is obtained from both mass matrices, charged leptons giving rise to non-zero theta(l)(13) and neutrino masses giving rise to tri-bi-maximal mixing. The physical mixing angles are expressed by a simple relation between theta(l)(13) and tri-bi-maximal angles to fit the recent experimental results. The other model generates PMNS matrix with non-zero theta(13), only from the neutrino mass transformation. The 5-dimensional effective theory of Majorana neutrinos obtained in this framework is tested with phenomenological bounds in the parametric spaces sin theta(23), sin theta(12) and m(2)/m(3) vs. sin theta(13).