CONFRONTING SOLUTIONS TO THE ATMOSPHERIC NEUTRINO ANOMALY INVOLVING LARGE-ANGLE NU(MU)-]NU(E) OSCILLATIONS WITH SUPERKAMIOKANDE AND CHOOZ

Neutrino oscillation scenarios involving large angle mu(nu) --> nu(e) oscillations are disfavoured in the parameter range Delta m(2)/eV(2) g reater than or similar to 10(-3) by recent results from the CHOOZ reac tor-based <(nu)over bar>(e), disappearance experiment. For this reason we extend our previous work on up-down asymmetries for various oscill ation scenarios by computing up-down asymmetries and the R ratio for t he entire range of interest of Delta m(2). Matter effects in the Earth play a crucial role. We perform a chi(2) fit to the data. We find tha t, because of the matter effect, the three-flavour maximal mixing mode l provides a reasonable fit to SuperKamiokande and CHOOZ data provided that the relevant Delta m(2) is in the range 4 X 10(-4) less than or similar to Delta m(2)/eV(2) less than or similar to 1.5 X 10(-3) (C) 1 998 Published by Elsevier Science B.V. All rights reserved.