The lepton masses and mixings are studied on the basis of string inspired $SU(6)times SU(2)_R$ model with global flavor symmetries. Provided that sizable mixings between lepton doublets $L$ and Higgsino-like fields $H_d$ with even R-parity occur and that seesaw mechanism is at work in the neutrino sector, the model can yield a large mixing angle solution with $tan theta_{12}, tan theta_{23} = O(sqrt{l})$ $({l}= 0.22)$, which is consistent with the recent experimental data on atmospheric and solar neutrinos. In the solution Dirac mass hierarchies in the neutrino sector cancel out with the heavy Majorana sector in large part due to seesaw mechanism. Hierarchical pattern of charged lepton masses can be also explained.
Download