CONSTRAINTS ON BARYON-NONCONSERVING YUKAWA COUPLINGS IN A SUPERSYMMETRIC THEORY

The one-loop evolution of couplings in the minimal supersymmetric stan dard model, extended to include baryon nonconserving (B) operators thr ough explicit R-parity violation, is considered keeping only B superpo tential terms involving the maximum possible number of third generatio n superfields. If all retained Yukawa couplings Y(i) are required to r emain in the perturbative domain (Y(i)<1) up to the scale of gauge gro up unification, upper bounds ensue on the magnitudes of the B coupling strengths at the supersymmetry-breaking scale, independent of the mod el of unification. They tum out to be similar to the corresponding fix ed point values reached from a wide range of Y(i) (including all Y(i) greater than unity) at the unification scale. The coupled evolution of the top quark and B Yukawa couplings results in a reduction of the fi xed point value of the former.