paper

Four-loop QCD analysis of the Bjorken sum rule vs data

arXiv:1106.6352 · doi:10.1016/j.physletb.2011.11.023

Abstract

We study the polarized Bjorken sum rule at low momentum transfers in the range with the four-loop NLO expression for the coefficient function in the framework of the common QCD perturbation theory (PT) and the singularity-free analytic perturbation theory (APT). The analysis of the PT series for gives a hint to its asymptotic nature manifesting itself in the region GeV. It relates to the observation that the accuracy of both the three- and four-loop PT predictions happens to be at the same 10% level. On the other hand, the usage of the two-loop APT allows one to describe the precise low energy JLab data down to MeV and gives a possibility for reliable extraction of the higher twist (HT) corrections. At the same time, above MeV the APT two-loop order with HT is equivalent to the four-loop PT with HT compatible to zero and is adequate to current accuracy of the data.

6 pages, 7 figures

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