Grand unification of μ-τ symmetry

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 theta(13) and looking for its correlation with theta(23) - pi/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 theta(13) from its zero mu-tau symmetric value to a nonzero value keeping it under an upper limit. (C) 2006 Elsevier B.V. All rights reserved.