QCD sum rule calculation of γγ* → π0 transition form factor

We discuss QCD sum rule analysis of the form factor Fγ^*γ^*π^o( q², Q²) in the region where virtuality of one of the spacelike photons is small q² ≪ 1 GeV ² while another is large: Q² ≳ 1 GeV ². Our approach, in contrast to pQCD, does not require explicit assumptions about the shape of the pion distribution amplitude φ _π( X). The absolute value of the 1/ Q² term obtained in this paper favours φ _π( X) close to the asymptotic form φ _π^as( X) = 6 ƒ _πx (1 - x).