FERMION SPECTRA AND KM MATRICES IN A LEFT-RIGHT-SYMMETRICAL MODEL FROM CALABI-YAU STRING COMPACTIFICATION

We study a left-right symmetric type of the effective low-energy theor y induced from the four-generation superstring model. The spontaneous breaking of the R-parity occurs through a nonzero vacuum expectation v alue (VEV) of the fourth generation right-handed sneutrino (v(R)). It is predicted that the lightest chargino is lighter than 113 GeV. By vi rtue of the seesaw mechanism we can explain the smallness of neutrino masses for three generations and the largeness of the fourth generatio n neutrino mass. The mixing in the color-singlet sector yields nontriv ial KM matrices which bring about flavor-changing interactions. If we take v(R) = O(10 TeV), our results are consistent with the current dat a except for the solar neutrino problem.