Grand Unification with Anomalous U(1) Symmetry and Non-abelian Horizontal Symmetry

Abstract

Non-abelian horizontal symmetry has been considered to solve potentially SUSY flavor problem, but simple models are suffering from various problems. In this talk, we point out that (anomalous) U(1)_A gauge symmetry solves all the problems in a natural way, especially, in the E_6 grand unified theories. Combining the GUT scenario with anomalous U(1)_A gauge symmetry, in which doublet-triplet splitting and natural gauge coupling unification are realized, and realistic quark and lepton mass matrices are obtained including bi-large neutrino mixings, complete E_6* SU(3)_H (or E_6*SU(2)_H) GUTs can be obtained, in which all the three generation quarks and leptons are unified into a single multiplet (27,3) (or two multiplets (27,2+1)). This talk is based on Ref.[1].

Comments: 10 pages, Talk given at "Strong Coupling Gauge Theories and Effective Field Theories"(SCGT02) conference at Nagoya, Japan, December 10-13,2002 Reference added