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Bounds on $ΔB=1$ Couplings in the Supersymmetric Standard Model

The most general supersymmetric model contains baryon number violating terms of the form $λ_{ijk}\;\ov{D}_i\, \ov{D}_j\, \ov{U}_k$ 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 $λ_{dsu}$ coupling; they do provide a bound on the $λ_{dbu}$ coupling, which we calculate. We find that the best bound on $λ_{dsu}$ arises from double nucleon decay into two kaons; the calculation is discussed in detail. 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.