Atmospheric and Solar neutrinos in the light of the SuperKamiokande results

Abstract

The hierarchy $\Delta m_{atm}^2\gg \Delta m_{\odot }^2$ and the large ${\theta }_{23}$ 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 $m_{atm}\equiv (\Delta m_{atm}^2{)}^{1/2}\approx 0.03eV$; 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.

8 pages, lecture at Erice 98