Study of hidden-charm, doubly-strange pentaquarks in $\Lambda_b\to J/\psi \Xi^- K^+$ and $\Xi_b\to J/\psi \Xi^- \pi^+$

Abstract

Hidden-charm pentaquark states with double strangeness, $P_{css}$, have been predicted within the framework of unitary coupled-channel dynamics. In this work, we theoretically investigate the potential to observe these states in the decays $\Lambda_b\to J/\psi \Xi^-K^+$ and $\Xi_b\to J/\psi\Xi^-\pi^+$. In this framework, these pentaquark configurations couple strongly to the $J/\psi\Xi$ channel, as well as to other vector-baryon channels with the $\bar c c s s n$ flavor structure, making these decay modes promising for their observation through the corresponding invariant-mass distributions. Our analysis begins with the identification of the dominant weak decay mechanisms, followed by hadronization into meson-baryon channels, connected through flavor symmetry. Final-state interactions are then incorporated to dynamically generate the full amplitude, accounting for the formation of the pentaquark states. We compare our results with recent LHCb measurements of the $J/\psi\Xi^-$ mass distribution and find that, given the predicted pentaquark width of about 10 MeV in this channel, the state is too narrow to be resolved with the current experimental resolution, but it would become visible with significantly improved mass precision.