Exploration of the LHCb $P_c$ states and possible resonances in a unitary coupled-channel model

TL;DR

This study models the interactions of hidden-charm pentaquark states using a coupled-channel approach, identifying potential resonances and their properties relevant to LHCb pentaquark observations.

Contribution

It extends previous models by including the $J/ar{D}^{(*)} o J/ar{D}^{(*)}$ channels and fits experimental data to predict new resonance states.

Findings

Four key states influence observables, with two at 1/2^- and two at 3/2^-.

Coupling strengths suggest how to detect these states experimentally.

Indications of higher partial wave states with larger widths.

Abstract

We extend our previous study of the interactions of $\bar{D}^{(*)} \Lambda_c - \bar{D}^{(*)}\Sigma_c^{(*)}$ within an analytic, unitary, coupled-channel approach by including the $J/\psi p$ channel and performing fits to the $J/\psi p$ invariant mass distributions in the $\Lambda_b^0 \to J/\psi p K^-$ decay by the LHCb Collaboration. We take into account the contributions of $t$-channel pseudoscalar and vector meson exchanges and $u$-channel baryon exchanges in this work, and a series of bound states and resonances with different spin-parities are dynamically generated. According to the results, four states have a significant impact on the physical observables, with two having a spin-parity of $1/2^-$ and the other two having $3/2^-$. These states can be associated with the LHCb hidden-charm pentaquarks. We further provide the coupling strength between each pole and different channels, which provides some insights on how to search for them in future experiments. Moreover, we also search for poles in higher partial waves up to $J=7/2$ and find indications for the existence of several states with larger widths.