Nucleon spin structure and perturbative QCD frontier on the move

作者：Pasechnik Roman S^*; Shirkov Dmitry V; Teryaev Oleg V; Solovtsova Olga P; Khandramai Vyacheslav L

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2010, 81(1): 016010.

DOI：10.1103/PhysRevD.81.016010

We discuss the interplay between higher orders of the perturbative QCD expansion and higher-twist contributions in the analysis of recent Jefferson Lab data on the lowest moments of spin-dependent proton and neutron structure functions Gamma(p,n)(1)(Q(2)) and Bjorken sum rule function Gamma(p-n)(1)(Q(2)) at 0.05 < Q(2) < 3 GeV2. We demonstrate that the values of the higher-twist coefficients mu(p,n)(2k) extracted from the mentioned data by using the singularity-free analytic perturbation theory provide a better convergence of the higher-twist series than with the standard perturbative QCD. From the high-precision proton data, we extract the value of the singlet axial charge a(0)(1 GeV2) = 0.33 +/- 0.05. We observe a slow Q(2) dependence of fitted values of the twist coefficient mu(4) and a(0) when going to lower energy scales, which can be explained by the well-known renormalization group evolution of mu(4)(Q(2)) and a(0)(Q(2)). As the main result, a good quantitative description of all the Jefferson Lab data sets down to Q similar or equal to 350 MeV is achieved.

• 出版日期2010-1