THREEFOLD MAXIMAL LEPTON MIXING AND THE SOLAR AND ATMOSPHERIC NEUTRINO DEFICITS

Threefold maximal mixing would imply a cyclic permutation symmetry amo ng the generations. The data from solar and atmospheric neutrino exper iments are consistent with such mixing, and require a hierarchical spe ctrum of mass-squared differences for the neutrinos. A fit for the two independent mass-squared differences (excluding only the HOMESTAKE so lar 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 cas e that the neutrino mass spectrum is qualitatively similar to that of the charged leptons and quarks, these results can be re-expressed in t erms 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.