Reanalysis the pentaquark $\Theta^+(1540)$ in the framework of QCD sum   rules approach with direct instantons
  In this article, we study the pentaquark state $ \Theta^+(1540)$ with a (scalar)diquark-(pseudoscalar)diquark-antiquark type interpolating current in the framework of the QCD sum rules approach by including the contributions from the direct instantons. The numerical results indicate that the contributions from the direct instantons are very small and can be safely neglected. 
Zhi-Gang Wang (NCEPU), Wei-Min Yang (USTC), Shao-Long Wan (USTC)