Y(3940) as a Mixed Charmonium-Molecule State

Abstract

Using the QCD sum rules approach we study the mass and decay width of the channel $J/\psi + \omega$ for the $Y(3940)$ state. We assume that it can be described by a mixed charmonium-molecule scalar state, $(\chi_{c0})-(D^\ast D^\ast)$ current, with $J^{PC} = 0^{++}$ quantum numbers. For the mixing angle $(76.0 \pm 5.0)^0$, we obtain the value $M = (3.95 \pm 0.11)$ GeV for the mass, which is in good agreement with the experimental mass of the $Y(3940)$ state. For the decay width into the channel $Y \rightarrow J/\psi + \omega$, we find the value $\Gamma_Y = (1.7 \pm 0.6)$ MeV, which is also compatible with the experimental data. We thus conclude that the present description of the $Y(3940)$ as a mixed charmonium-molecule state is a possible scenario to explain the structure of this state.