Simplest Neutrino Mixing from S4 Symmetry
Abstract
In 2004, two of us proposed a texture, the "Simplest" neutrino mass matrix, which predicted sin(theta13)=sqrt((2 Solar-Delta m2)/(3 Atm-Delta m2)) and deltaCP=90 degrees. Using today's measured values for neutrino mass-squared differences, this prediction gives sin2(theta13)~0.086+0.003-0.006, compared with a measured value, found by averaging the results of the Daya Bay and RENO experiments, of sin2(theta13)=0.093+0.010-0.010. Here we present a specific model based on S4 symmetry leading to this successful texture in the context of the type-1 see-saw mechanism, assuming Majorana neutrinos. In this case, slightly different predictions are obtained relating theta13 to the light neutrino masses, which are in accord with current experimental limits and testable at future experiments. Large CP asymmetries remain a generic prediction of the texture.