X(1835) as a baryonium state with QCD sum rules
  In this article, we take the point of view that the X(1835) be a baryonium state and calculate its mass within the framework of the QCD sum rules approach. The numerical value of the mass of the X(1835) is consistent with the experimental data. There may be some baryonium component in the X(1835) state. 
Zhi-Gang Wang (NCEPU), Shao-Long Wan (USTC)