Tribimaximal mixing, leptogenesis, and θ13θ13

We show that seesaw models based on flavor symmetries (such as A4A4 and Z7⋊Z3Z7⋊Z3) which produce exact tribimaximal neutrino mixing also imply a vanishing leptogenesis asymmetry. We show that higher order symmetry breaking corrections in these models can give a non-zero leptogenesis asymmetry and generically also give deviations from tribimaximal mixing and a non-zero θ13≳10−2θ13≳10−2.