Large or Small Angle MSW from Single Right-Handed Neutrino Dominance

Abstract

In this talk we discuss a natural explanation of both neutrino mass hierarchies {\it and} large neutrino mixing angles, as required by the atmospheric neutrino data, in terms of a single right-handed neutrino giving the dominant contribution to the 23 block of the light effective neutrino matrix, and illustrate this mechanism in the framework of models with U(1) family symmetries. Sub-dominant contributions from other right-handed neutrinos are required to give small mass splittings appropriate to the MSW solution to the solar neutrino problem. We present three explicit examples for achieving the small angle MSW solution in the framework of U(1) family symmetry models containing three right-handed neutrinos, which can naturally describe all quark and lepton masses and mixing angles. In this talk we also extend the analysis to the large angle MSW solution.

Invited talk at 6th Topical Seminar on Neutrino and Astroparticle Physics, San Miniato, Italy, 17-21 May 1999. Submitted to Nucl.Phys.B.Proc.Suppl

References in corpus (6)

• Evidence for oscillation of atmospheric neutrinos
• Measurement of a small atmospheric ${\nu }_{\mu }/{\nu }_e$ ratio
• Study of the atmospheric neutrino flux in the multi-GeV energy range
• Atmospheric and Solar Neutrinos with a Heavy Singlet
• Family Symmetry and Neutrino Mixing
• Bi-Maximal Neutrino Mixing in the MSSM with a Single Right-Handed Neutrino