19 research outputs found
Exploring the neutrino mass matrix at M_R scale
We discuss the neutrino mass matrix which predicts zero or small values of
|V_{13}| in MSSM and found the inequality, sin^2 2theta_{12} <= sin^2
2theta_sol, where sin^2 2theta_{12} is the mixing angle at M_R scale and sin^2
2theta_{sol} is the value determined by the solar neutrino oscillation. This
constraint says that the model which predicts a larger value of tan^2
theta_{sol} at M_R than the experimental value is excluded. In particular, the
bi-maximal mixing scheme at M_R scale is excluded, from the experimental value
tan^2 theta_sol<1. In this model, |V_{13}| and a Dirac phase at m_Z are induced
radiatively and turn out to be not small. The effective neutrino mass is
expected to be of order 0.05 eV.Comment: revtex4, 20 pages, 6 figure
The Problem of Large Leptonic Mixing
Unlike in the quark sector where simple permutation symmetries can
generate the general features of quark masses and mixings, we find it
impossible (under conditions of hierarchy for the charged leptons and without
considering the see-saw mechanism or a more elaborate extension of the SM) to
guarantee large leptonic mixing angles with any general symmetry or
transformation of only known particles. If such symmetries exist, they must be
realized in more extended scenarios.Comment: RevTeX, 4 pages, no figure