Nearly tri-bimaximal neutrino mixing and CP violation from μ-τ symmetry breaking

Assuming the Majorana nature of massive neutrinos, we generalize the Friedberg-Lee neutrino mass model to include CP violation in the neutrino mass matrix M-v. We show that a favorable neutrino mixing pattern (with theta(12) approximate to 35.3 degrees, theta(23) = 45 degrees, theta(13) not equal 0 degrees and delta = 90 degrees) can naturally be derived from M-v if it has an approximate or softly-broken mu-tau symmetry. We point out a different way to obtain the nearly tri-bimaximal neutrino mixing with delta = 0 degrees and non-vanishing Majorana phases. The most general case, in which all the free parameters of M-v are complex and the resultant neutrino mixing matrix contains both Dirac and Majorana phases of CP violation, is also discussed. (c) 2006 Elsevier B.V. All rights reserved.