Instanton Induced Charged Fermion and Neutrino Masses in a U(3)_C×U(3)_L×U(3)_R Gauge Symmetry

Using instanton effects, we consider a U(3)_C×U(3)_L×U(3)_R gauge symmetry obtained from intersecting D6-branes. This is equivalent to the trinification model extended by the three U(1) factors that survive as global symmetries in the low energy effective model. In the corresponding three-stack, the fermion masses are induced by the possible stringy corrections to the corresponding superpotential by using E2-instantons. Using the known data with neutrino masses m_vτ～1 eV, we show the magnitudes of the relevant scales.