A consistent three-flavour approach to possible evidence of neutrino oscillations

Abstract

We thoroughly analyse the interplay of the two possible indications of neutrino masses and mixing 3- the solar ν-deficit and the atmospheric f-anomaly — and their compatibility with the negative results of oscillation searches at accelerators and reactors. First, world neutrino data — with the exception of upward-going muons and multi-GeV atmospheric v's — are analysed in a three-flavour oscillation framework, characterized by an extremized form of the natural neutrino mass hierarchy. A set of solutions is found in the neutrino mass/mixing parameter space. Then these solutions are shown to be stable by means of a perturbative-like approach, leading to a definitely reasonable and consistent hierarchical scenario. Solar and Earth matter effects on neutrino propagation are accurately taken into account in both steps of the analysis. Finally, the recent Kamiokande results on the atmospheric ν μ/ν e ratio in the multi-GeV energy range are compared with our fits of non-solar ν data. The impressive agreement reinforces our oscillation scenario.