Model of Large Mixing Angle MSW Solution

We have obtained the neutrino mass matrix with the large mixing angle (LMA) MSW solution, sin 2θ⊙ = 0.65 ∼ 0.97 and ∆m⊙ = 10 −5 ∼ 10−4eV2, in the S3L × S3R flavor symmetry. The structure of our neutrino mass matrix is found to be stable against radiative corrections. The solar neutrino data as well as the atmospheric one give big impact on the study of the lepton mass matrices. There is a typical texture of the lepton mass matrix with the nearly maximal mixing of flavors, which is derived from the symmetry of the lepton flavor democracy [1, 2], or from the S3L×S3R symmetry of the left-handed Majorana neutrino mass matrix [3, 4]. This texture have given a prediction for the neutrino mixing sin 2θatm = 8/9. The mixing for the solar neutrino depends on the symmetry breaking pattern of the flavor such as sin 2θ⊙ = 1 or ≪ 1. However, the LMA-MSW solution, sin 2θ⊙ = 0.65 ∼ 0.97 and ∆m⊙ = 10 −5 ∼ 10−4eV [5], has not been obtained in the previous works [1, 2, 3, 4]. We study how to get the LMA-MSW solution in the S3L × S3R symmetric mass matrices, and discuss the stability of the neutrino mass matrix against radiative corrections. The texture of the charged lepton mass matrix was presented based on the S3L × S3R symmetry as follows [1, 3, 6]: Ml = cl 3 