Hidden-charm pentaquarks as a meson-baryon molecule with coupled channels for D ¯ ( ) Λ c and D ¯ ( ) Σ c ( )

The recent observation of two hidden-charm pentaquark states by LHCb collaborations prompted us to investigate the exotic states close to the D¯Λc, D¯*Λc, D¯Σc, D¯Σc*, D¯*Σc and D¯*Σc* thresholds. We therefore studied the hadronic molecules that form the coupled-channel system of D¯(*)Λc and D¯(*)Σc(*). As the heavy quark spin symmetry manifests the mass degenerations of D¯ and D¯* mesons, and of Σc and Σc* baryons, the coupled channels of D¯(*)Σc(*) are important in these molecules. In addition, we consider the coupling to the D¯(*)Λc channel whose thresholds are near the D¯(*)Σc(*) thresholds, and the coupling to the state with nonzero orbital angular momentum mixed by the tensor force. This full coupled-channel analysis of D¯(*)Λc−D¯(*)Σc(*) with larger orbital angular momentum has never been performed before. By solving the coupled-channel Schrödinger equations with the one meson exchange potentials with respect to the heavy quark spin and chiral symmetries, we studied the hidden-charm hadronic molecules with I(JP)=1/2(3/2±) and 1/2(5/2±). We conclude that the JP assignment of the observed pentaquarks is 3/2+ for Pc+(4380) and 5/2− for Pc+(4450), which is in agreement with the results of the LHCb analysis. In addition, we give predictions for other JP=3/2± states at 4136.0, 4307.9 and 4348.7 MeV in JP=3/2−, and 4206.7 MeV in JP=3/2+, which can be further investigated by means of experiment.