Strong decays of higher charmonium states into open-charm meson pairs

Abstract

The open-charm strong decays of higher charmonium states up to the mass of the $6P$ multiplet are systematically studied in the $^{3}{P}_{0}$ model. The wave functions of the initial charmonium states are calculated in the linear potential and screened potential quark models. The decay widths for most of the well-established charmonium states above the open-charm thresholds can be reasonably described. By comparing our quark model calculations with the experimental observations we also discuss the nature of some of the newly observed charmonium-like states. It is found that (i) the $\ensuremath{\psi}(4415)$ may favor the $\ensuremath{\psi}(4S)$ or ${\ensuremath{\psi}}_{1}(3D)$ assignment. There may exist two highly overlapping vector charmonium states around 4.4 GeV; (ii) in the LP model the ${J}^{PC}={1}^{\ensuremath{-}\ensuremath{-}}$ $Y(4660)$ resonance and the ${J}^{PC}={0}^{++}$ $X(4500)$ resonance may be assigned as the $\ensuremath{\psi}(5S)$ and ${\ensuremath{\chi}}_{c0}(4P)$, respectively; (iii) the newly observed state ${X}^{*}(3860)$ can be assigned as the ${\ensuremath{\chi}}_{c0}(2P)$ state with a narrow width of about 30 MeV; (iv) it seems to be difficult to accommodate the $X(4140)$ and $X(4274)$ states in the same potential model as excited ${\ensuremath{\chi}}_{c1}$ states; (v) the $X(3940)$ resonance can be assigned as the ${\ensuremath{\eta}}_{c}(3S)$ state; (vi) the vector charmonium-like states $Y(4230/4260,4360)$ and scalar $X(4700)$ cannot be described by any conventional charmonium states self-consistently in our model.