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 νμ→ντ oscillations are favored, νμ→νe 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 νμ↔νe and νe→ντ oscillations in future long-baseline experiments.