Nuclear effects in neutrino-nucleus interactions

The apparent anomaly in the ratio of muon-to-electron atmospheric neutrinos has been confirmed by several collaborations using different detection tec hniques. Together with the asymmetry in the zenithal distributions of the n u(mu) events in Super-Kamiokande, it gives a strong support to the neutrino oscillation hypothesis and to the existence of a non-vanishing mass for th e neutrinos. In this work we are interested in the role of nuclear physics in the neutrino-oxygen reactions, which are relevant for the Cherenkov dete ctors. We point out that multi-nucleon excitations of np-nh type and nuclea r correlations could modify an experimental analysis a la Super-Kamiokande because they lead to a substantial enhancement of the number of 1 Cherenkov ring retained events. (C) 2000 Elsevier Science B.V. All rights reserved.