LHCb pentaquarks in constituent quark models

TL;DR

This paper investigates the nature of recently observed pentaquark states at LHCb using a constituent quark model, finding molecular state interpretations and predicting additional states near certain thresholds.

Contribution

It applies a constrained constituent quark model to analyze LHCb pentaquarks as molecular states and predicts new states near other thresholds.

Findings

Identified molecular states consistent with observed pentaquarks.

Predicted two additional states near specific meson-baryon thresholds.

Discussed decay widths to assign possible identities of the states.

Abstract

The recently discovered $P_c(4380)^+$ and $P_c(4450)^+$ states at LHCb have masses close to the $\bar D\Sigma_c^*$ and $\bar D^*\Sigma_c$ thresholds, respectively, which suggest that they may have significant meson-baryon molecular components. We analyze these states in the framework of a constituent quark model which has been applied to a wide range of hadronic observables, being the model parameters, therefore, completely constrained. The $P_c(4380)^+$ and $P_c(4450)^+$ are studied as molecular states composed by charmed baryons and open charm mesons. Several bound states with the proper binding energy are found in the $\bar D\Sigma_c^*$ and $\bar D^*\Sigma_c$ channels. We discuss the possible assignments of these states from their decay widths. Moreover, two more states are predicted, associated with the $\bar D\Sigma_c$ and $\bar D^* \Sigma_c^*$ thresholds.