Results on neutrino masses and mixing

by M. REBELO (CERN - TH)

Thursday 18 Jan 2001, 14:00 → 15:00 Europe/Zurich

TH Auditorium (CERN)

We have studied mixing and CP violation of three left-handed Majorana neutrinos in the limit of exactly degenerate masses showing that in this limit the leptonic mixing matrix is parametrized only by two angles and one phase; after lifting of the degeneracy this parametrization accommodates the present data on atmospheric and solar neutrinos as well as double beta decay. Some of the leptonic mixing ansätze suggested in the literature correspond to special cases of this parametrization. We were able to accommodate the current experimental bounds on leptonic masses and mixing with a simple ansatz for neutrino and charged lepton masses, leading to quasi-degenerate neutrinos, where all entries of each mass matrix have equal moduli and the flavour dependence is only in their phases. We have analysed how phenomenologically viable neutrino masses and mixing can be generated whithin the framework of the seesaw mechanism together with a set of reasonable assumptions.