2013, Vol.16, No.1, pp.93-98
We present progress in the QCD analysis of the Bjorken sum rule at low momentum transfers. We study asymptotic structure of the perturbative QCD expansion at low Q² scales based on analysis of recent accurate data on the Bjorken sum rule and available now four-loop expression for the coefficient-function CBj(Q²). We demonstrate that the standard perturbative series for CBj(Q²) gives a hint to its asymptotic nature manifesting itself in the region Q²< 1GeV². It is confirmed by the considered integral model for the perturbative QCD correction. We extract a value of higher-twist μ4 coefficient and study the interplay between higher orders and higher-twist contributions. Results of other approaches to the description of Bjorken sum rule data are discussed.
Key words:
perturbation theory, deep-inelastic scattering, QCD analysis, higher twists
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