Y(4260) as a mixed charmonium-tetraquark state
  Using the QCD sum rule approach we study the Y(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 $\theta \approx (53.0\pm 0.5)^{0}$, we obtain a value for the mass which is in good agreement with the experimental mass of the Y(4260). However, for the decay width we find the value $\Ga_Y \approx (1.0\pm 0.2)$ MeV which is not compatible with the experimental value $\Ga \approx (88\pm 23)$ MeV. Therefore, we conclude that, although we can explain the mass of the Y(4260), this state cannot be described as a mixed charmonium-tetraquark state since, with this assumption, we can not explain its decay width. 
J. M. Dias, R. M. Albuquerque, M. Nielsen and C. M. Zanetti
hep-ph hep-ex