# Heavy quark spin symmetric molecular states from ${\bar D}^{(*)}\Sigma_c^{(*)}$ and other coupled channels in the light of the recent LHCb pentaquarks

## TL;DR

This paper models pentaquark states as molecular states of heavy mesons and baryons, successfully reproducing observed LHCb pentaquarks and predicting additional states consistent with experimental hints.

## Contribution

It introduces a heavy quark spin symmetric approach using an extended local hidden gauge model, fitting only one parameter to reproduce and predict pentaquark states.

## Key findings

- Reproduces three LHCb pentaquarks with quantum numbers and structures.
- Predicts additional states around 4374 MeV and 4520 MeV consistent with experimental hints.
- Identifies a state at 5/2^- that does not couple to $J/\psi p$ in S-wave.

## Abstract

We consider the ${\bar D}^{(*)}\Sigma_c^{(*)}$ states, together with $J/\psi N$ and other coupled channels, and take an interaction consistent with heavy quark spin symmetry, with the dynamical input obtained from an extension of the local hidden gauge approach. By fitting only one parameter to the recent three pentaquark states reported by the LHCb collaboration, we can reproduce the three of them in base to the mass and the width, providing for them the quantum numbers and approximate molecular structure as $1/2^-$ $\bar{D} \Sigma_c$, $1/2^-$ $\bar{D}^* \Sigma_c$, and $3/2^-$ $\bar{D}^* \Sigma_c$, and isospin $I=1/2$. We find another state around 4374 MeV, of $3/2^-$ $\bar{D} \Sigma_c^*$ structure, for which indications appear in the experimental spectrum. Two other near degenerate states of $1/2^-$ $\bar{D}^* \Sigma_c^*$ and $3/2^-$ $\bar{D}^* \Sigma_c^*$ nature are also found around 4520 MeV, which although less clear, are not incompatible with the observed spectrum. In addition, a $5/2^-$ $\bar D^* \Sigma_c^*$ state at the same energy appears, which however does not couple to $J/\psi p$ in $S-$wave, and hence it is not expected to show up in the LHCb experiment.