Model of Geometric Neutrino Mixing
  Current neutrino oscillation data from solar, atmospheric, and reactor experiments are consistent with the neutrino mixing matrix elements taking values sin^2\theta_{12} = 1/3, sin^2\theta_{23} = 1/2, and sin^2\theta_{13}=0. We present a class of renormalizable gauge models which realize such a geometric mixing pattern naturally. These models, which are based on the non--Abelian discrete symmetry A_4, place significant restrictions on the neutrino mass spectrum, which we analyze. It is shown that baryogenesis via leptogenesis occurs quite naturally, with a single phase (determined from neutrino oscillation data) appearing in leptonic asymmetry and in neutrinoless double beta decay. Such predicted correlations would provide further tests of this class of models. 
K.S. Babu and Xiao-Gang He