QCD sum rules: form factors and wave functions
Abstract
The 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 \varphi_\pi(x) are unreliable, so that the humpy shape of \varphi_\pi (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.
Cite
@article{arxiv.hep-ph/9707335,
title = {QCD sum rules: form factors and wave functions},
author = {A. V. Radyushkin},
journal= {arXiv preprint arXiv:hep-ph/9707335},
year = {2007}
}
Comments
10 pages, to be published in the Proceedings of Conference on Perspectives in Hadronic Physics, Trieste,12-16 May 1997