Discriminating horizontal symmetries from operator analysis and proton-decay experiments

The impact of different horizontal symmetries on nucleon decay is discussed within the framework of the standard and the left-right-symmetric theory. Under very general assumptions of operator analysis, it is demonstrated that U(1)/sub H/, SU(2)/sub H/, SU(3)/sub H//sup V/L, and SU(3)/sub H//sup V/ symmetries predict different nucleon decay modes and, hence, the on-going proton-decay experiments can be used to discriminate among the different horizontal symmetries. Furthermore, it is shown that, under favorable situations, the standard and the left-right-symmetric theory can also be distinguished