The Sum Rules for Structure Functions of Polarized $e(μ)N$ Scattering: Theory vs. Experiment
Abstract
Description
The determination of twist-4 corrections to the structure functions of polarized $e(μ)N$ scattering by QCD sum rules is reviewed and critically analyzed. It is found that in the case of the Bjorken sum rule the twist-4 correction is small at $Q^2 > 5 GeV^2$. However, the accuracy of the today experimental data is insufficient to reliably determine $α_s$ from the Bjorken sum rule. For the singlet sum rule -- $p+n$ -- the QCD sum rule gives only the order of magnitude of twist-4 correction. At low and intermediate $Q^2$ the model is presented which realizes a smooth connection of the Gerasimov-Drell-Hearn sum rules at $Q^2 = 0$ with the sum rules for $Γ_{p,n}(Q^2)$ at high $Q^2$. The model is in a good agreement with the experiment.
Talk at the Workshop Spin-97, Dubna, July 1997, to be published in Proceedings, 10 pages, LaTeX 2e, 3 eps figures included using epsf.sty
Talk at the Workshop Spin-97, Dubna, July 1997, to be published in Proceedings, 10 pages, LaTeX 2e, 3 eps figures included using epsf.sty