THREEFOLD MAXIMAL LEPTON MIXING AND THE SOLAR AND ATMOSPHERIC NEUTRINO DEFICITS

Threefold maximal mixing would imply a cyclic permutation symmetry among the generations. The data from solar and atmospheric neutrino experiments are consistent with such mixing, and require a hierarchical spectrum of mass-squared differences for the neutrinos. A fit for the two independent mass-squared differences (excluding only the HOMESTAKE solar neutrino result) yields: Delta m(2) = (0.72 +/- 0.18) x 10(-2) eV(2) and Delta m'(2) < 0.9 x 10(-11) eV(2) at 90% confidence, In the case that the neutrino mass spectrum is qualitatively similar to that of the charged leptons and quarks, these results can be re-expressed in terms of the neutrino masses as follows: m(3) similar or equal to 85 +/- 10 meV, and m(1), m(2) < 3 mu eV at 90% confidence. Implications for future experiments are discussed.