Large Mixing Angle MSW Solution in U(1) Flavor Symmetry

Abstract

We have discussed the quark-lepton mass matrices with the U(1) flavor symmetry in SU(5), which lead to the large mixing angle MSW solution of solar neutrinos. The solar neutrino solution depends on the next-leading terms in the neutrino mass matrix. We have found the lepton mass matrices with the $U(1)\times Z_2$ symmetry, which give the LMA-MSW solution uniquely. The coefficients of the matrix elements of the charged leptons are constrained strongly due to the bound of $U_{e3}$ in the CHOOZ experiment.