Neutrino mixing: A4 variations

Abstract

In the context of the non-Abelian discrete symmetry A4, the neutrino mass matrix has been studied extensively. A brief update is presented to focus on the conceptual shift from tribimaximal mixing (θ13=0, θ23=π/4, tan2⁡θ12=1/2) to cobimaximal mixing (θ13≠0, θ23=π/4, δCP=±π/2) which agrees well with present data. Three specific realistic examples are proposed, two with three and the third with just two parameters.