Atmospheric and Solar neutrinos in the light of the SuperKamiokande results

The hierarchy ∆matm ≫ ∆m⊙ and the large θ23 mixing angle, as suggested by neutrino oscillation experiments, can be accounted for by a variety of lepton flavour models. A dichotomy emerges: i) Models were all neutrino masses are bounded by matm ≡ (∆matm) 1 2 ≈ 0.03eV ; ii) Models of quasi-degenerate neutrinos. It is shown how these different patterns of neutrino masses may arise from different lepton flavour symmetries. Physical implications are discussed in the various cases. ∗Lecture given at the 98 Erice School. This work was supported in part by the TMR Network under the EEC Contract No. ERBFMRX CT960090.