QCD ANALYSIS OF THE BJORKEN SUM RULE REVISITED

摘要

We present extended analysis of the polarized Bjorken sum rule using the four-loop expression for the coefficient function C_(Bj)(α_s) available now and the recent low-Q~2 data from the Jefferson Lab and COMPASS experiments. We demonstrate that the perturbative series for the function C_(Bj) gives a hint to its asymptotic nature manifesting itself in the region Q~2 approx＜ 1 GeV~2. It is confirmed by the considered integral model for the perturbative QCD correction. We analyze values of higher twist terms extracted from the mentioned data and discuss the interplay between higher orders perturbative and higher twist contributions. We extend our consideration to the Gross-Llewellyn Smith sum rule and investigate the relation between higher twist coefficients in these two sum rules.