Generalized neutrino mixing from the atmospheric anomaly

We determine the neutrino mixing and mass parameters that are allowed by the Super-Kamiokande atmospheric neutrino data in a three-neutrino model with one mass-squared difference contributing to the oscillations. We find that although nu(mu) --> nu(tau) oscillations are favored, nu(mu) --> nu(e) oscillations with amplitude as large as 0.18 are allowed even after accounting for the limit from the CHOOZ reactor experiment. The range of allowed parameters permit observable nu(mu) --> nu(e) and nu(e) --> nu(tau) oscillations in future long-baseline experiments. (C) 1998 Elsevier Science B.V. All rights reserved.