Original scientific paper
Pion structure in QCD: From theory to lattice to experimental data
A. P. Bakulev
; Bogoliubov Lab. of Theoretical Physics, JINR, 141980 Dubna, Russia
S. V. Mikhailov
; Bogoliubov Lab. of Theoretical Physics, JINR, 141980 Dubna, Russia
A. V. Pimikov
; Bogoliubov Lab. of Theoretical Physics, JINR, 141980 Dubna, Russia
N. G. Stefanis
; ITP-II, Ruhr-Universität Bochum, D-44780 Bochum, Germany
Abstract
We describe the present status of the pion distribution amplitude (DA) as it originates from several sources: (i) a nonperturbative approach based on QCD sum rules with nonlocal condensates, (ii) an O(αs) QCD analysis of the CLEO data on F γγ∗π (Q2 ) with asymptotic and renormalon models for higher twists and (iii) recent high-precision lattice QCD calculations of the second moment of the pion DA. We show predictions for the pion electromagnetic form factor, obtained in analytic QCD perturbation theory, and compare it with the JLab data on Fπ(Q2 ). We also discuss in this context an improved model for nonlocal condensates in QCD and show its consequences for the pion DA and the γγ∗ → π transition form factor. We include a brief analysis of meson-induced massive lepton (muon) Drell–Yan production for the process π −N → µ +µ −X, considering both an unpolarized nucleon target and longitudinally polarized protons.
Keywords
pion distribution amplitude; electromagnetic form factors; QCD sum rules; factorization; renormalization group evolution; lattice QCD; Drell–Yan production
Hrčak ID:
304887
URI
Publication date:
4.5.2008.
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