Left-right symmetric model withμ↔τsymmetry

Abstract

We analyze the leptonic sector in the left-right symmetric model dressed with a $(Z_{2})^{3}$ discrete symmetry which realizes, after weak spontaneous breaking, a small broken $\mu\lra\tau$ symmetry that is suggested to explain observable neutrino oscillation data. $\mu\lra\tau$ symmetry is broken at tree level in the effective neutrino mass matrix due to the mass difference $\widetilde{m}_{\tau}\neq \widetilde{m}_{\mu}$ in the diagonal Dirac mass terms, whereas all lepton mixings arise from a Majorana mass matrix. In the limit of a small breaking we determined $\theta_{13}$, and the deviation from the maximal value of $\theta_{ATM}$, in terms of the light neutrino hierarchy scale, $m_{3}$, and a single free parameter $h_{s}$ of the model.