LHCb pentaquarks in constituent quark models

Abstract

The recently discovered $P_c(4380{)}^{+}$ and $P_c(4450{)}^{+}$ states at LHCb have masses close to the $\bar{D}{\Sigma }_c^{\ast }$ and ${\bar{D}}^{\ast }{\Sigma }_c$ 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 $\bar{D}{\Sigma }_c^{\ast }$ and ${\bar{D}}^{\ast }{\Sigma }_c$ 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 ${\bar{D}}^{\ast }{\Sigma }_c^{\ast }$ thresholds.

Comments: 5 pages, 2 tables