Further evidence for threefold maximal lepton mixing and a hierarchical spectrum of neutrino mass-squared differences

The phenomenological case for threefold maximal lepton mixing is strengthened by more detailed comparison with existing data. The atmospheric neutrino data are self-consistent and in good agreement with the threefold maximal mixing prediction R = 2/3 (chi(2)/DOF = 4.3/5, CL = 51%). Including partially-contained event data, the zenith angle dependence also points to threefold maximal mixing, ruling out a range of mixing schemes, including that of Fritzsch and Xing. Accounting for de facto uncertainties in solar neutrino fluxes, the solar neutrino data (including HOMESTAKE) are shown to be consistent with threefold maximal mixing (chi(2)/DOF = 5.1/3, CL = 16%), as is the upper limit from the LSND appearance experiment. Detailed predictions for forthcoming long-base-line reactor and accelerator experiments are presented. (C) 1997 Published by Elsevier Science B.V.