Grand Unification with Anomalous U(1) Symmetry

In this talk, we introduce a new scenario of grand unified theory (GUT) with anomalous $U(1)_A$ gauge symmetry. Since generic interactions (including non-renormalizable interactions) are introduced, once we fix the symmetry of the theory, we can define the theory without O(1) coefficients. The number of parameters to determine the symmetry is just 11 or 12 integer parameters which are anomalous $U(1)_A$ charges(integer) for introduced multiplets. It is surprising that the GUT scenario can explain doublet-triplet splitting, quark and lepton masses and mixing angles. In neutrino sector, the scenario realizes LMA solution for solar neutrino problem and large $U_{e3}=O(0.1)$. Moreover, the scenario predicts that the unification scale becomes smaller than the usual GUT scale, namely proton decay via dimension 6 operators may be seen in future experiments. This talk is based on the papers\cite{maekawa,maekawa2,maekawa3,BM,MY}.