The Interference between Continuum and Resonance in e+e- -> ccbar   Experiment
  e+e- experiments at charmonium production threshold are reviewed, it is found that the contribution of the continuum process via virtual photon has been neglected in almost all the experiments and most channels analyzed. It is pointed out that the contribution of the continuum part may affect the final results significantly in psi(2S) and psi(3770) decays, while the interference between the continuum amplitude and the resonance amplitude may even affect the J/psi decays as well as the psi(2S) and psi(3770). This leads to the revise of the analysis of strong and electromagnetic amplitude in psi(2S) decays, including psi(2S) ->VP which is the long lasting puzzle between J/psi and psi(2S) decays. For psi(3770) physics, a large constructive interference for light hadron modes and destructive interference for DDbar could be responsible for the discrepancy between the larger cross section of inclusive hadrons by direct measurement of e+e- -> psi(3770)-> hadrons than the DDbar cross section measured using D single-tag and double-tag method. 
P. Wang, C.Z. Yuan, X.H. Mo and D.H. Zhang