Search for the pentaquark state inψ(2S)andJ/ψdecays toKS0pK−n̄andKS0p¯K+n

Results are presented on $\ensuremath{\psi}(2S)$ and $J/\ensuremath{\psi}$ hadronic decays to ${K}_{S}^{0}{\mathrm{pK}}^{\ensuremath{-}}\mathrm{n\ifmmode \bar{}\else \={}\fi{}}$ and ${K}_{S}^{0}\overline{p}{K}^{+}n$ final states from data samples of 14 million $\ensuremath{\psi}(2S)$ and 58 million $J/\ensuremath{\psi}$ events accumulated at the BES II detector. No $\ensuremath{\Theta}(1540)$ signal, the pentaquark candidate, is observed, and upper limits are set for $\mathcal{B}(\ensuremath{\psi}(2S)\ensuremath{\rightarrow}\ensuremath{\Theta}\overline{\ensuremath{\Theta}}\ensuremath{\rightarrow}{K}_{S}^{0}{\mathrm{pK}}^{\ensuremath{-}}\mathrm{n\ifmmode \bar{}\else \={}\fi{}}{+K}_{S}^{0}\overline{p}{K}^{+}n)l0.84\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ and $\mathcal{B}(J/\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\psi}}\ensuremath{\Theta}\overline{\ensuremath{\Theta}}\ensuremath{\rightarrow}{K}_{S}^{0}{\mathrm{pK}}^{\ensuremath{-}}\mathrm{n\ifmmode \bar{}\else \={}\fi{}}{+K}_{S}^{0}\overline{p}{K}^{+}n)l1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. For single $\ensuremath{\Theta}(1540)$ production, the upper limits determined by our analysis are also on the order of ${10}^{\ensuremath{-}5}$ in both $\ensuremath{\psi}(2S)$ and $J/\ensuremath{\psi}$ decays.