Tribimaximal Mixing, Leptogenesis, and theta13

TL;DR

This paper explores how flavor symmetry-based seesaw models that produce tribimaximal neutrino mixing inherently predict zero leptogenesis asymmetry, but higher order corrections can generate non-zero asymmetry and deviations like a measurable theta13.

Contribution

It demonstrates that symmetry-based models with tribimaximal mixing naturally lead to zero leptogenesis, but higher order corrections can produce observable leptogenesis asymmetry and deviations from tribimaximal mixing.

Findings

Higher order symmetry breaking induces non-zero leptogenesis asymmetry.

Deviations from tribimaximal mixing include a theta13 >~ 10^(-2).

Models can produce observable leptogenesis effects with small symmetry breaking.

Abstract

We show that seesaw models based on flavor symmetries (such as A_4 and Z_7 X Z_3) 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 theta13 >~ 10^(-2)