CHARM 2013: X(4260) as a Mixed Charmonium-Tetraquark State

Using the QCD sum rule approach we study the X(4260) state assuming that it can be described by a mixed charmonium-tetraquark current with $J^{PC}=1^{--}$ quantum numbers. For the mixing angle around $\theta=(53.0 \pm 0.5)^0$, we obtain a value for the mass which is in good agreement with the experimental mass of the X(4260). For the decay width into the channel $X \to J/\psi \pi \pi$, we find the value $\Gamma_{X \to J/\psi\pi\pi}=(4.1 \pm 0.6)$ MeV, which is much smaller than the total experimental width $\Gamma = (108\pm 12)$ MeV. However, considering the experimental upper limits for the decay of the X(4260) into open charm, we conclude that we cannot rule out the possibility of describing this state as a mixed charmonium-tetraquark state.