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 techniques. Together with the asymmetry in the zenithal distributions of the νμ events in Super-Kamiokande, it gives a strong support to the neutrino oscillation hypothesis and to the existence of a non-vanishing mass for the neutrinos. In this work we are interested in the role of nuclear physics in the neutrino-oxygen reactions, which are relevant for the Cherenkov detectors. We point out that multi-nucleon excitations of np–nh type and nuclear correlations could modify an experimental analysis à la Super-Kamiokande because they lead to a substantial enhancement of the number of 1 Cherenkov ring retained events.