Group space scan of flavor symmetries for nearly tribimaximal lepton mixing

Abstract

We present a systematic group space scan of discrete Abelian flavor symmetries for lepton mass models that produce nearly tribimaximal lepton mixing. In our models, small neutrino masses are generated by the type-I seesaw mechanism. The lepton mass matrices emerge from higher-dimension operators via the Froggatt-Nielsen mechanism and are predicted as powers of a single expansion parameter that is of the order of the Cabibbo angle θC 0.2. We focus on solutions that can give close to tribimaximal lepton mixing with a very small reactor angle θ13 ≈ 0 and find several thousand explicit such models that provide an excellent fit to current neutrino data. The models are rather general in the sense that large leptonic mixings can come from the charged leptons and/or neutrinos. Moreover, in the neutrino sector, both left- and right-handed neutrinos can mix maximally. We also find a new relation θ13(3) for the reactor angle and a new sum rule θ23 ≈ π/4+/(2)1/2 for the atmospheric angle, allowing the models to be tested in future neutrino oscillation experiments.