QCD sum rules and soft-hard interplay for hadronic form factors
Abstract
We discuss two types of contributions to hadronic form factors in QCD: hard gluon exchange and soft wave function overlap. Within the QCD sum rule approach, the hard contribution has strong numeric suppression by factor (\alpha_s/\pi) ~ 0.1 for each exchange. For this reason, the soft contribution dominates at accessible momentum transfers. The ``humpy'' distribution amplitudes used to enhance hard terms cannot be derived from QCD sum rules in a self-consistent way. The estimates of soft terms obtained within the local quark-hadronic duality approach in all cases are close to existing data, providing an experimental evidence that hard terms are small.
- Publication:
-
arXiv e-prints
- Pub Date:
- November 1998
- DOI:
- 10.48550/arXiv.hep-ph/9811225
- arXiv:
- arXiv:hep-ph/9811225
- Bibcode:
- 1998hep.ph...11225R
- Keywords:
-
- High Energy Physics - Phenomenology
- E-Print:
- 9 pages, Latex, 1 figure