Constraints on baryon-nonconserving Yukawa couplings in a supersymmetric theory

The one-loop evolution of couplings in the minimal supersymmetric standard model, extended to include baryon nonconserving (B/) operators through explicit R-parity violation, is considered keeping only B/ superpotential terms involving the maximum possible number of third generation superfields. If all retained Yukawa couplings Yᵢ are required to remain in the perturbative domain (Yᵢ1) up to the scale of gauge group unification, upper bounds ensue on the magnitudes of the B/ coupling strengths at the supersymmetry-breaking scale, independent of the model of unification. They turn out to be similar to the corresponding fixed point values reached from a wide range of Yᵢ (including all Yᵢ greater than unity) at the unification scale. The coupled evolution of the top quark and B/ Yukawa couplings results in a reduction of the fixed point value of the former.