Deep inside the pion. Reconciling QCD theory with data

Abstract

Recent developments in the QCD description of the pion structure are reviewed. The CLEO pion-photon transition data analysis favors a distribution amplitude for the pion that is double-humped but endpoint-suppressed. After a short outline of the derivation of this amplitude from QCD sum rules with nonlocal condensates, we present the fully fledged analysis of the CLEO data prefaced by predictions for the $F^{\gamma \rho \pi }$ form factor and commenting on the inherent theoretical uncertainties due to higher twists and NNLO perturbative corrections. We supplement our discussion by considering within QCD factorization theory, the electromagnetic pion form factor at NLO accuracy on one hand, and diffractive di-jets production on the other, comparing our predictions with the respective experimental data from JLab and the Fermilab E791 collaboration. In all cases, the agreement is impressive.

10 pages, 5 figures consisting of 8 eps files. Contribution to the Festschrift on the occasion of Klaus Goeke's 60th birthday, to appear in Annalen der Physik

References in corpus (2)

• Pion form factor in QCD: From nonlocal condensates to NLO analytic perturbation theory
• Light quark masses, chiral condensate and quark-gluon condensate in quenched lattice QCD with exact chiral symmetry

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