Lepton mixing predictions from S4 in the tridirect CP approach to two right-handed neutrino models

摘要

We perform an exhaustive analysis of all possible breaking patterns arising from S 4 ? H C P in a new tridirect C P approach to the minimal seesaw model with two right-handed neutrinos, and construct a realistic flavor model along these lines. According to this approach, separate residual flavor and C P symmetries persist in the charged lepton, “atmospheric” and “solar” right-handed neutrino sectors, i.e., we have three symmetry sectors rather than the usual two of the semidirect C P approach (charged leptons and neutrinos). Following the tridirect C P approach , we find 26 kinds of independent phenomenologically interesting mixing patterns. Eight of them predict a normal ordering (NO) neutrino mass spectrum and the other 18 predict an inverted ordering (IO) neutrino mass spectrum. For each phenomenologically interesting mixing pattern, the corresponding predictions for the Pontecorvo-Maki-Nakagawa-Sakata matrix, the lepton mixing parameters, the neutrino masses and the effective mass in neutrinoless double beta decay are given in a model-independent way. One breaking pattern with an NO spectrum and two breaking patterns with IO spectra correspond to form dominance. We find that the lepton mixing matrices of three kinds of breaking patterns with NO spectra and one form dominance breaking pattern with an IO spectrum preserve the first column of the tribimaximal mixing matrix, i.e., yield a TM1 mixing matrix.