Grand unification of $\hat{I}¼-\ddot{I}„$ Symmetry

Abstract

Near maximal neutrino mixing needed to understand atmospheric neutrino data can be interpreted to be a consequence of an interchange symmetry between the muon and tau neutrinos in the neutrino mass matrix in the flavor basis. This idea can be tested by a measurement of the neutrino mixing parameter $\hat{I}{¸}_{13}$ and looking for its correlation with $\hat{I}{¸}_{23}-\ddot{I}€/4$. We present a supersymmetric SU(5) grand unified model for quarks and leptons which obeys this exchange symmetry and is a realistic model that can fit all observations. GUT embedding shifts $\hat{I}{¸}_{13}$ from its zero $\hat{I}¼-\ddot{I}„$ symmetric value to a nonzero value keeping it under an upper limit.

13 pages and 4 figures