A4 family symmetry and quark-lepton unification

We present a model of quark and lepton masses and mixings based on A(4) family symmetry, a discrete subgroup of an SO(3) flavour symmetry, together with Pati-Salam unification. It accommodates tri-bimaximal neutrino mixing via constrained sequential dominance with a particularly simple vacuum alignment mechanism emerging through the effective D-term contributions to the scalar potential. (c) 2007 Elsevier B.V. All rights reserved.