A minimal see-saw model for hierarchical neutrino masses with large mixing

Abstract

The atmospheric and solar neutrino oscillation data suggest hierarchical neutrino masses with at least one large mixing. The simplest see-saw models for reconciling the two features are U (1) extensions of the SM with flavour dependent gauge charges. I discuss a minimal model of this type containing two heavy right-handed neutrinos, which have normal Dirac couplings to ν µ and ν τ but suppressed ones to ν e . It can naturally account for the large (small) mixing solutions to the atmospheric (solar) neutrino oscillation data.