Proton decay in a consistent supersymmetric SU(5) GUT model

It is widely believed that minimal supersymmetric SU(5) GUTs have been excluded by the SuperKamiokande bound for the proton decay rate. However, in the minimal model, the theoretical prediction assumes unification of Yukawa couplings, Y-d = Y-e, which is known to be badly violated. We analyze the implications of this fact for the proton decay rate. In a consistent SU(5) model with higher dimensional operators, where SU(5) relations among Yukawa couplings hold, the proton decay rate can be several orders of magnitude smaller than the present experimental bound. (C) 2003 Elsevier Science B.V. All rights reserved.