Bounds on $\Delta B=1$ Couplings in the Supersymmetric Standard Model

The most general supersymmetric model contains baryon number violating terms of the form $\lm_{ijk}\ \ov{D}_i\ \ov{D}_j\ \ov{U}_k$ in the superpotential. We reconsider the bounds on these couplings, assuming that lepton number conservation ensures proton stability. These operators can mediate $n-\ov{n}$ oscillations and double nucleon decay. We show that neutron oscillations do not, as previously claimed, constrain the $\lm_{dsu}$ coupling; they do provide a bound on the $\lm_{dbu}$ coupling, which we calculate. We find that the best bound on $\lm_{dsu}$ arises from double nucleon decay into two kaons. There are no published limits on this process; experimenters are urged to examine this nuclear decay mode. Finally, the other couplings can be bounded by the requirement of perturbative unification.