Pseudo-Dirac solar neutrinos

Three of the viable solutions of the solar neutrino problem are consistent with close to maximal leptonic mixing: sin(2) theta (12) = 1/2 (1 - epsilon (12)) with \epsilon (12)\ << 1. Flavor models can naturally explain close to maximal mixing if approximate horizontal symmetries force a pseudo-Dirac structure on the neutrino mass matrix. An experimental determination of \epsilon (12)\ and sign (epsilon (12)) can constrain the structure of the lepton mass matrices and consequently provide stringent tests of such flavor models. If both \epsilon (12)\ and Deltam(21)(2) are known, it may be possible to estimate the mass scale of the pseudo-Dirac neutrinos. Radiative corrections to close to maximal mixing are negligible. Subtleties related to the kinetic terms in Froggatt-Nielsen models are clarified.