Testing leptonic SU(2) horizontal symmetry using neutrino mixings

Abstract

After some preliminary arguments suggesting that neutrino mixings with inverted mass pattern may be easier to understand within the framework of a local horizontal symmetry SU(2)_H acting on leptons, we construct a specific extension of the minimal supersymmetric standard model that implements the idea and analyze its predictions. We show that the horizontal symmetry leads to an experimentally testable relation between the neutrino parameters U_{e3} and the ratio of solar and atmospheric mass difference squared i.e. U^2_{e3} cos 2 theta_{odot} = (Delta m^2_{odot})/(2 Delta m^2_A) + O(U^4_{e3}, (m_e/m_mu)^2). Taking the solar neutrino parameters inferred from present data at 99.7% confidence level, the above relation leads to a lower bound on U_{e3} >= 0.08 and an allowed region in the U_{e3} and (Delta m^2_{odot})/(2 Delta m^2_A) space which can be tested in proposed long baseline experiments.

Comments: 11 pages, one figure; model made supersymmetric, final conclusions unchanged, new references added