Hidden-charm pentaquarks as a meson-baryon molecule with coupled channels for (D)over-bar(*) Λc and (D)over-bar(*)Σc(*)

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