Consequences of approximate $S_3$ symmetry of the neutrino mass matrix

Assuming that the neutrino mass matrix is dominated by a term with the permutation symmetry $S_3$ it is possible to explain neutrino data only if the masses are quasidegenerate. A subdominant term with an approximate $\mu -\tau$ symmetry leads to an approximate tribimaximal form. Experimental consequences are discussed.

Figure 1

The solar neutrino survival ${sin}^2{\theta }_{12}$ for the higher-energy neutrinos for the MSW solution as a function of $\frac{ϵ}{t}$.

Figure 2

Diagram with ${tan}^2{\theta }_{23}-1$ vs $\sin {\theta }_{13}$.