Lattice study on $\eta_{c2}$ and X(3872)
  Properties of $2^{-+}$ charmonium $\eta_{c2}$ are investigated in quenched lattice QCD. The mass of $\eta_{c2}$ is determined to be 3.80(3) GeV, which is close to the mass of $D$-wave charmonium $\psi(3770)$ and in agreement with quark model predictions. The transition width of $\eta_{c2}\to \gamma J/\psi$ is also obtained with a value $\Gamma=3.8(9)$ keV. Since the possible $2^{-+}$ assignment to X(3872) has not been ruled out by experiments, our results help to clarify the nature of X(3872). 
Yi-Bo Yang, Ying Chen, Long-Cheng Gui, Chuan Liu, Yu-Bin Liu, Zhaofeng   Liu, Jian-Ping Ma, and Jian-Bo Zhang
hep-lat hep-ex hep-ph