Flavor symmetry L-mu-L-tau and quasidegenerate neutrinos

摘要

Current data implies three simple forms of the neutrino mass matrix, each corresponding to the conservation of a nonstandard lepton charge. While models based on L-e and L-e-L-mu-L-tau are well known, little attention has been paid to L-mu-L-tau. A low-energy mass matrix conserving L-mu-L-tau implies quasidegenerate light neutrinos. Moreover, it is mu-tau symmetric and therefore (in contrast to L (e) and L-e-L-mu-L-tau) automatically predicts maximal atmospheric neutrino mixing and zero U-e3. A seesaw model based on L-mu-L-tau is investigated and testable predictions for the neutrino mixing observables are given. Renormalization group running below and in between the seesaw scales is taken into account in our analysis, both numerically and analytically.