THE ALIGNED SU(5)X U(1)(2) MODEL

In Calabi-Yau string compactification, it is pointed out that there ex ists a new type of SU(5) x U(1)(2) model (the aligned SU(5)x U(1)2 mod el) in which the SU(5) differs from the standard SU(5) and also from t he flipped SU(5). With the aid of the discrete symmetry suggested from Gepner model, we propose a simple and phenomenologically interesting three-generation model with the aligned SU(5) x U(1)(2) gauge symmetry . The triplet-doublet splitting problem can be solved. It is also foun d that there is a realistic solution for solar neutrino problem and fo r the mu-problem. At low energies this model is in accord with the min imal supersymmetric standard model except for the existence of singlet fields with masses of O(1)TeV.