Tri - bimaximal Neutrino Mixing and θ 13

We propose an extension of tri-bimaximal mixing to include a non-zero reactor angle θ13 while maintaining the tri-bimaximal predictions for the atmospheric angle θ23 = 45 o and solar angle θ12 = 35 . We show how such tri-bimaximalreactor mixing can arise at leading order from realistic GUT models with nonAbelian discrete family symmetry spontaneously broken by flavons with vacuum alignment, based on the see-saw mechanism and partially constrained sequential dominance. E-mail: [email protected] Over the last decade neutrino physics has undergone a revolution with the measurement of neutrino mass and lepton mixing from a variety of solar, atmospheric and terrestrial neutrino oscillation experiments [1]. Lepton mixing is described by the 3× 3 matrix [2]