Perturbative effects in the form factor γγ*→π0 and extraction of the pion distribution amplitude from CLEO data -: art. no. 116002

We study the pion form factor F-pi gamma gamma*(Q(2)) in the light-cone sum rule approach, accounting for radiative corrections and higher twist effects. Comparing the results to the CLEO experimental data on F-pi gamma gamma*(Q(2)), we extract the pion distribution amplitude of twist 2. The deviation of the distribution amplitude from the asymptotic one is small and is estimated to be a(2)(mu) = 0.12+/-0.03 at mu = 2.4 GeV, in the model with one nonasymptotic term. The ansatz with two nonasymptotic terms gives some region of a(2) and a(4), which is consistent with the asymptotic distribution amplitude, but does not agree with some old models.