Possible explanation of the discrepancy of the light-cone QCD sum rule   calculation of g(D*Dpi) coupling with experiment
  The introduction of an explicit negative radial excitation contribution in the hadronic side of the light cone QCD sum rule (LCSR) of Belyaev, Braun, Khodjamirian and Ruckl, can explain the large experimental value of g(D*Dpi), recently measured by CLEO. At the same time, it considerably improves the stability of the sum rule when varying the Borel parameter. 
D.Becirevic, J.Charles, A.LeYaouanc, L.Oliver, O.Pene and J.C.Raynal