gamma+gamma --> pi+pi, K+K : leading term QCD vs handbag model
  The "handbag" model was proposed as an alternative, at the present day energies, to the leading term QCD predictions for some hard exclusive processes. The recent precise data from the Belle Collaboration on the large angle cross sections $\gamma\gamma --> \pi\pi, KK $ allow a check of these two approaches to be performed. It is shown that the handbag model fails to describe the data from Belle, while the leading term QCD predictions are in reasonable agreement with these data 
Victor L. Chernyak