2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/47084The shape of hadronic distribution amplitudes (DAs) is a critical issue for the perturbative QCD of hard exclusive processes. Recent CLEO data on gamma gamma* -> pi^0 form factor clearly favor a pion DA close to the asymptotic form. We argue that QCD sum rules for the moments of the pion DA φ_π(x) are unreliable, so that the humpy shape of φ_π(x) obtained by Chernyak and Zhitnitsky is a result of model assumptions rather than an unambigous consequence of QCD sum rules. This conclusion is also supported by a direct QCD sum rule calculation of the gamma gamma* -> pi^0 form factor which gives a result very close to the CLEO data.10 pages, to be published in the Proceedings of Conference on Perspectives in Hadronic Physics, Trieste,12-16 May 1997High Energy Physics - Phenomenologytext