$(B+L)$-conserving Nucleon Decays in Supersymmetric Models

The presence of the $(B+L)$-conserving decay modes $n\to K^{+}{e}^{-},$ $n \to K^+ \mu^-,$ $p\to K^{+}{e}^{-}{\pi }^{+}$ and $p\to K^{+}{\mu }^{-}{\pi }^{+}$ is shown to be a characteristic feature of a class of models with explicit breaking of $R$-parity. These modes dominate over the $(B-L)$-conserving ones in certain regions of the parameter space; the impact of this scenario for nucleon decay search at the Super-Kamiokande is discussed.