Molecular components in P-wave charmed-strange mesons
Pablo G. Ortega🇨🇭 · Jorge Segovia🇩🇪 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸
Results obtained by various experiments show that the and mesons are very narrow states located below the and thresholds, respectively. This is markedly in contrast with the expectations of naive quark models and heavy quark symmetry. Motivated by a recent lattice study which addresses the mass shifts of the ground states with quantum numbers () and () due to their coupling with -wave thresholds, we perform a similar analysis within a nonrelativistic constituent quark model in which quark-antiquark and meson-meson degrees of freedom are incorporated. The quark model has been applied to a wide range of hadronic observables and thus the model parameters are completely constrained. The coupling between quark-antiquark and meson-meson Fock components is done using a model in which its only free parameter has been elucidated performing a global fit to the decay widths of mesons that belong to different quark sectors, from light to heavy. We observe that the coupling of the meson sector to the threshold is the key feature to simultaneously lower the masses of the corresponding and states predicted by the naive quark model and describe the meson as the state of the doublet predicted by heavy quark symmetry, reproducing its strong decay properties. Our calculation allows to introduce the coupling with the -wave channel and the computation of the probabilities associated with the different Fock components of the physical state.