Pentaquark Search and Other Multiquark Candidates at BES

Abstract

Results are presented on $ψ(2S)$ and $J/ψ$ hadronic decays to $K^0_SpK^-\bar n$ and $K^0_S\bar p K^+n$ final states from data samples of 14 million $ψ(2S)$ and 58 million $J/ψ$ events accumulated at the BES II detector. No $Θ(1540)$ signal, the pentaquark candidate, is observed, and the upper limits are set. We also present a narrow enhancement near $2m_p$ in the invariant mass spectrum of $p \bar{p}$ pairs from $J/ψ\to γp \bar{p}$ decays, an enhancement near the $m_p + M_Λ$ mass threshold and an enhancement near the $m_K + m_Λ$ mass threshold from $J/ψ\to p K^- \barΛ + c.c.$ decays, based on 58 million $J/ψ$ events.