Power corrections to Bjorken and Gross-Llewellyn Smith sum rules in QCD

Bjorken unpolarized and polarized sum rules: comparative analysis of large-NF expansions

“…They allow comparison with models for the O(1/Q 2 ) contributions to both F 1 and xF 3 , obtained within the framework of an infrared renormalon approach, which predicts similar x-dependence of these two power corrections [4]. A second point of interest is comparison with QCD sum rule estimates [5] for the twist-4 matrix element introduced in Ref. [6] which gives an O(1/Q 2 ) correction to the unpolarized Bjorken sum rule (Bjunp SR)…”

The αS3 approximation of quantum chromodynamics to the Ellis-Jaffe sum rule

“…For the Bjorken sum rule, the α s correction [11], the α 2 s correction [12], and the α 3 s correction [13] have been calculated in the leading twist approximation. Higher twist corrections have also been calculated [14]. The Ellis-Jaffe sum rule 1 0 dxg p/n 1 (x, Q 2 ) for the proton and neutron was calculated to order α s [15] and to order α 2 s [16] in the leading twist approximation.…”

“…(14,18) are obtained in an arbitrary covariant gauge for the gluon field. This means that we keep the gauge parameter ξ that appears in the gluon propagator i [−g µν + (1 − ξ)q µ q ν /(q 2 + iǫ)]/(q 2 + iǫ) as a free parameter in the calculations.…”

The Strong Coupling Constant

“…The perturbative QCD-correction [23] is known to O(α 3 s ). A measurement of the strong coupling constant taking into account also non-perturbative ("higher twist") terms [24] has been performed by the NuTeV-Collaboration [25] at a scale µ = 1.73 GeV, based on the old CCFR data.…”