Quark model estimate of hidden-charm pentaquark resonances

A quark model, which reproduces the ground-state mesons and baryons, i.e., the threshold energies, is applied to the qqqc (c) over bar configurations, where q is a light quark and c the charmed quark. In the calculation, several open channels are explicitly included such as J/psi + N, eta(c) + N, Lambda(c) + (D) over bar , etc. To distinguish genuine resonances and estimate their width, we employ the Gaussian expansion method supplemented by the real scaling method (stabilization). No resonance is found at the energies of the P-c (4380) and P-c (4450) pentaquarks. On the other hand, there is a sharp resonant state at 4690 MeV with a J = 1/2(-) state and another one at 4920 MeV with a J = 3/2(-) state which have a compact structure.