Search for the Pentaquark State in $\psi(2S)$ and $J/\psi$ Decays to $K^0_SpK^-\bar n$ and $K^0_S\bar p K^+n$

TL;DR

This study searched for the pentaquark candidate $ ext{Theta}(1540)$ in $ ext{psi}(2S)$ and $J/ ext{psi}$ decays but found no evidence, setting upper limits on its production rates in these decays.

Contribution

First search for $ ext{Theta}(1540)$ in $ ext{psi}(2S)$ and $J/ ext{psi}$ decays with large data samples, establishing upper limits on its production.

Findings

No $ ext{Theta}(1540)$ signal observed.

Upper limits on branching fractions are set at $< 10^{-5}$ level.

Results constrain models predicting pentaquark production in charmonium decays.

Abstract

Results are presented on $\psi(2S)$ and $J/\psi$ hadronic decays to $K^0_SpK^-\bar n$ and $K^0_S\bar p K^+n$ final states from data samples of 14 million $\psi(2S)$ and 58 million $J/\psi$ events accumulated at the BES II detector. No $\Theta(1540)$ signal, the pentaquark candidate, is observed, and upper limits for ${\cal B}(\psi(2S)\to\Theta\bar\Theta\to K^0_S p K^-\bar n + K^0_S \bar p K^+ n) < 0.84\times 10^{-5}$ and ${\cal B}(J/\psi\to\Theta\bar\Theta\to K^0_S p K^-\bar n + K^0_S \bar p K^+ n) < 1.1\times 10^{-5}$ at the 90% confidence level are set. For single $\Theta(1540)$ production, the upper limits determined by our analysis are also on the order of $10^{-5}$ in both $\psi(2S)$ and $J/\psi$ decays.