Models and Phenomenology of Neutrino Masses circa 2010

Abstract

We review recent developments in models of neutrino masses and mixing. Emphases are given to models based on finite group family symmetries from which the tri-bimaximal neutrino mixing can arise. In particular, we describe one recent model based on SUSY SU(5) combined with a family symmetry based on the double tetrahedral group, T'. All 22 observable fermion masses and mixing angles and CP violating measures are fitted with only 9 parameters. In this model, a near tri-bimaximal MNS matrix and a realistic CKM matrix are simultaneously generated; the MNS matrix gets slightly modified by virtue of having the Georgi-Jarlskog relations. Due to the presence of complex Clebsch-Gordan coefficients in T', CP violation in this model is entirely geometrical in origin. The prediction of the model for the leptonic Dirac CP phase is 227 degrees, which turns out to be very close to the current best fit value of 220 degrees from SuperK.