$S_3$ Symmetry and Tri-bimaximal Mixing

Abstract

The near maximal value for the atmospheric neutrino mixing angle together with the fact that the solar mixing angle satisfies the relation ${\sin }^2\hat{I}{¸}_{\odot }\simeq 1/3$ is the basis for the so called tri-bimaximal mixing (tbm) when $\hat{I}{¸}_{13}=0$. In this note, we explore the possibility that tri-bimaximal mixing is an indication of a softly broken higher leptonic symmetry $S_3$, the permutation of three lepton families that embeds the $\hat{I}¼-\ddot{I}„$ exchange symmetry of leptons.

8 pages and three figures