Four-neutrino mass spectra and the Super-Kamiokande atmospheric up-down asymmetry - art. no. 073007

In the framework of schemes with mixing of four massive neutrinos, which ca n accommodate the atmospheric, solar and LSND ranges of Delta m(2) and cont ain three active neutrinos and a sterile one, we show that, in the whole re gion of Delta m(LSND)(2) allowed by LSND, the Super-Kamiokande up-down asym metry excludes all mass spectra with a group of three close neutrino masses separated from the fourth mass by the LSND gap of order 1 eV. Only two sch emes with mass spectra in which two pairs of close masses ore separated by the LSND gap can describe the Super-Kamiokande up-down asymmetry and all ot her existing neutrino oscillation data. [S0556-2821(99)03419-0].