Two/Three-Flavor Oscillation and MSW/Vacuum Oscillation Solution of Neutrinos in the SO(3) Gauge Model

Abstract

Three interesting scenarios for neutrino mixing, i.e., (i) small-large mixing scenario, (ii) nearly bi-maximal mixing scenario and (iii) three-flavor oscillation scenario, are analyzed in connection with three possible assignments of the maximal CP-violating phase after spontaneous symmetry breaking of SO(3) in a model with gauged SO(3) lepton flavor symmetry. As a consequence, it is found that the scenario (ii) is more reliable to be resulted in reconciling both solar and atmospheric neutrino data. Though three Majorana neutrino masses in all scenarios can be nearly degenerate, in the scenarios (ii) and (iii) masses of the neutrinos are allowed to be large enough to play a significant cosmological role and in the scenario (i) the fraction $\Omega_{\nu}/\Omega_{m}$ is bounded to be $\Omega_{\nu}/\Omega_{m} < (4-10)%$ for $\Omega_{m} = (1.0-0.4)$ and $h=0.6$.