A natural framework for bi-large neutrino mixing

In this Letter we present a “natural” framework for obtaining bi-large neutrino mixing incorporating the Frampton–Glashow–Yanagida neutrino mass matrix ansatz. We show that an SU(2)×U(1) family symmetry can provide the desired FGY neutrino mass ansatz in a minimal supersymmetric standard model. We also show how to obtain an approximate FGY ansatz in an SO(10) SUSY GUT. In this context, the same SU(2)×U(1) family symmetry also generates the hierarchy of fermion masses as well as ameliorating SUSY flavor problems.