QCD sum rule study for hidden-strange pentaquarks

TL;DR

This paper uses QCD sum rules to predict the masses of hidden-strange pentaquark states, finding they are above relevant thresholds and unlikely to form bound states, aligning with current experimental observations.

Contribution

It provides the first QCD sum rule analysis of hidden-strange pentaquarks in various configurations, predicting their masses and stability.

Findings

All predicted masses are above relevant thresholds.

No bound states are likely to form in studied channels.

Results agree with experimental non-observation.

Abstract

Inspired by the LHCb's observations of hidden-charm $P_{c(s)}$ states, we study their hidden-strange analogues $P_s$ states in both $[udu][\bar ss]$ and $[uds][\bar su]$ configurations. We investigate the $P_s$ pentaquark states in $p\eta^\prime$, $p\phi$, $\Lambda K$, $\Sigma K$ and $\Sigma^\ast K^\ast$ structures with $J^P = \frac{1}{2}^-$ and $\Sigma ^\ast K$ and $\Sigma K^\ast$ with $J^P = \frac{3}{2}^-$, and calculate their masses in the framework of QCD sum rules. Our numerical results show that the extracted hadron masses for all the $p\eta^\prime$, $p\phi$, $\Lambda K$, $\Sigma K$ and $\Sigma^\ast K^\ast$ structures are much higher than $\Sigma K$ mass threshold and masses for $\Sigma ^\ast K$ and $\Sigma K^\ast$ also higher than threshold of corresponding hadron, so that no bound state exists in such channels, which is consistent with the experimental status to date.