Vacuum Neutrino Oscillations of Solar Neutrinos and Lepton Mass Matrices

We consider the case that the solar neutrino deficit is due to the vacuum oscillation. The lepton mass matrices with nearly bi-maximal mixings are needed in order to explain both solar and atmospheric neutrino deficit. A texture with the symmetry of flavour democracy or $S_3$ has been investigated by taking account of the symmetry breaking terms of the charged lepton mass matrix. It is found that predicted mixings can be considerably changed from the neutrino mixings $\sin^2 2\th_\odot\simeq 1$ and $\sin^2 2\th_{\rm atm}\simeq 8/9$ at the symmetric limit. The correlation between $|U_{e3}|$ and $|U_{e1}U_{e2}^*|$ is also presented. The test of the model is discussed by focusing on the three flavor analyses in the solar neutrinos, atmospheric neutrinos and long baseline experiments.Comment: 11 pages, LaTex file, 2 figures included using epsfig, some mistakes corrected, references added, numerical results unchange

Large Mixing Angle MSW Solution in S_3 Flavor Symmetry

We have investigated phenomenological implications on the neutrino flavor mixings in the $S_{3L}\times S_{3R}$ symmetric mass matrices including symmetry breaking terms. We have shown how to get the large mixing angle MSW solution, $\sin^2 2 \th_\odot=0.65\sim 0.97$ and \Delta m_{\odot}^2= 10^{-5}\sim 10^{-4}\eV^2, in this model. It is found that the structure of the lepton mass matrix in our model is stable against radiative corrections although the model leads to nearly degenerate neutrinos.Comment: 14 pages, LaTex file, 1 figur

Prediction on CP Violation in Long Baseline Neutrino Oscillation Experiments

We predict CP violation in the long baseline accelerator experiments taking into consideration the recent LSND data and the atmospheric neutrino data. The estimated upper bound of CP violation is 0.006, which may be observable in the long baseline accelerator experiments. It is found that the upper bound increases to 0.01 if the LSND data is excluded. The matter effect, which is not CP invariant, is found to be very small in the case we consider.Comment: 23 pages, LaTex file, 4 figures included using epsfig fig.3 and 4 are added. To be published in PT

Impact of Ue3U_{e3} on Neutrino Models

We have discussed the impact of $U_{e3}$ on the model of the neutrino mass matrix. In order to get the small $U_{e3}$, some flavor symmetry is required. Typical two models are investigated. The first one is the model in which the bi-maximal mixing is realized at the symmetric limit. The second one is the texture zeros of the neutrino mass matrix.Comment: Invited talk presented at NOON200

Linking Leptonic CP violation to Quark Unitarity Triangle

We study the linking between the CP violating phase of the lepton sectors and the unitarity triangle of the B0 meson system. Antusch, King, Malinsky and Spinrath have shown that the quark mass matrices with the negligible 1-3 mixing give an interesting relation between the phase of the quark mixing matrices and CP violating measure phi_2(alpha). This approach is extended by considering the SO(10) GUT including the Pati-Salam symmetry, which links the Yukawa matrices of the quark sector to the one of the lepton sector. We discuss the relation of the CP violating phases between both quark and lepton sectors as well as the mixing angles. Then, the leptonic CP violating phase is predicted in terms of the angle of the unitarity triangle of the B0 meson system. The leptonic CP violating phase deltaPMNS is predicted in the region -74 to -89, which is the consistent with the recent T2K results. Our predicted phase is sensitive to phi_2(alpha) and phi_3(gamma). These predictions will be clearly tested in the future neutrino experiments as well as the Belle-II experiment.Comment: 14 pages, 8 figures, Some discussions and Appendix are adde