ABSTRACT
The evidence for solar and atmospheric neutrino oscillations is analysed in a three-flavour oscillation framework, including the most recent Super-Kamiokande data, as well as the constraints on νe mixing coming from the CHOOZ reactor experiment. The regions of the mass-mixing parameter space compatible with the data are determined and their features discussed. In particular, it is shown that bimaximal mixing (or nearly bimaximal mixing) of atmospheric and solar neutrinos is also possible within the MSW solution to the solar neutrino problem.
The recent atmospheric neutrino data from the Super-Kamiokande (SK) experiment [1] are in excellent agreement with the hypothesis of flavour oscillations in the νµ ↔ ντ channel [2]. Such a hypothesis is consistent with all the SK data, including sub-GeV e-like and µ-like events (SGe, µ), multiGeV e-like and µ-like events (MGe, µ), and upward-going muon events (UPµ), and is also corroborated by independent atmospheric neutrino results from the MACRO [3] and Soudan-2 [4] experiments. Oscillations in the νµ ↔ ντ channel are also compatible with the negative results of the reactor experiment CHOOZ in the νe ↔ νe channel [5, 6].
