R-parity violation in flavor-changing neutral current processes and top quark decays

We show that supersymmetric $R$-parity-breaking ($R_p$) interactions always result in flavor changing neutral current processes. Within a single coupling scheme, these processes can be avoided in either the charge $+\frac{2}{3}$ or the charge $-\frac{1}{3}$ quark sector, but not both. These processes are used to place constraints on $R_p$ couplings. The constraints on the first and the second generations are better than those existing in the literature. The $R_p$ interactions may result in new top quark decays. Some of these violate electron-muon universality or produce a surplus of $b$ quark events in $t\overline{t}$ decays. Results from the CDF experiment are used to bound these $R_p$ couplings.