Minimal supersymmetric SO(10) model and predictions for neutrino mixings and leptonicCPviolation

Abstract

We discuss a minimal supersymmetric SO(10) model where $B\ensuremath{-}L$ symmetry is broken by a 126 dimensional Higgs boson multiplet which also contributes to fermion masses in conjunction with a 10 dimensional superfield. This minimal Higgs boson choice provides a partial unification of neutrino flavor structure with that of quarks and has been shown to predict all three neutrino mixing angles and the solar mass splitting in agreement with observations, provided one uses the type II seesaw formula for neutrino masses. In this paper we generalize this analysis to include arbitrary CP phases in couplings and vacuum expectation values. We find that (i) the predictions for neutrino mixings are similar with ${U}_{e3}\ensuremath{\simeq}0.18$ as before and other parameters in a somewhat bigger range and (ii) that to first order in the quark mixing parameter $\ensuremath{\lambda}$ (the Cabibbo angle), the leptonic mixing matrix is CP conserving. We also find that in the absence of any higher dimensional contributions to fermion masses, the CKM phase is different from that of the standard model implying that there must be new contributions to quark CP violation from the supersymmetry breaking sector. Inclusion of higher dimensional terms however allows the standard model CKM phase to be maintained.