Nucleon spin structure and perturbative QCD frontier on the move
2010 (English)In: Physical Review D - Particles, Fields, Gravitation and Cosmology, ISSN 1550-7998, Vol. 81, no 1, 016010- p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2010. Vol. 81, no 1, 016010- p.
IdentifiersURN: urn:nbn:se:uu:diva-137894DOI: 10.1103/PhysRevD.81.016010ISI: 000274002800069OAI: oai:DiVA.org:uu-137894DiVA: diva2:378700