Abstract

We present a supersymmetric SU(5) X U(1)(H) model, free from gauge anomalies, where the Abelian factor U(1)(H), introduced to account for the hierarchy of fermion masses and mixings, is broken by the same adjoint representations of SU(5) that also break the GUT symmetry. The model predicts approximate, but never exact, b-tau Yukawa unification. The deviations are related to group theoretical coefficients and can naturally be at the level of 10-20%. (C) 2003 Elsevier B.V All rights reserved.