Reexamining the fermion mass relations in the supersymmetric SU(4)xO(4) GUT model

We study in detail the charged fermion masses in the context of the minimal Grand Unified Theory (GUT)- version of the supersymmetric SU (4) ''x'' O (4) model. We show how the presence of vacuum expectation values (VEVs) of the order of the GUT mass scale for the right-handed (RH) sneutrinos may modify the ''naive'' equality of the charged-lepton and the down-quark masses at MG = 1016 GeV. In particular, we indicate how one can successfully modify the problematic low-energy relation between ms and mμ, while preserving the good prediction mb/mr = r≅ 2.7 (r being the renormalization parameter). The fact that the VEVs of the RH sneutrinos are predicted to be of order ∼ MG, may also have interesting consequences in the mechanism of symmetry breaking of the model. (Author)