Search for the Rare Decays $J/\psi \to D_{S}^{-} \pi^{+}$, $J/\psi \to D^{-} \pi^{+}$, and $J/\psi \to \bar D^{0} \bar K^{0}$
Rare decay modes $J/\psi \to D_{S}^{-} \pi^{+} + c.c.$, $J/\psi \to D^{-} \pi^{+} + c.c.$, and $J/\psi \to \bar D^{0} \bar K^{0} + c.c.$ are searched for using 5.77$\times 10^{7}$ $J/\psi$ events collected with the BESII detector at the BEPC. No signal above background is observed. We present upper limits on the branching fractions $B(J/\psi \to D_{S}^{-} \pi^{+})$ $<$ 1.4$\times10^{-4}$, $B(J/\psi \to D^{-} \pi^{+})$ $<7.5\times10^{-5}$, and $B(J/\psi \to \bar D^{0} \bar K^{0})$ $<$ 1.7$\times10^{-4}$ at the 90% confidence level.