Next-to-leading order QCD analysis of polarized deep inelastic scattering data

Abstract

We present a next-to-leading order perturbative QCD analysis of world data on the spin dependent structure functions g1p, g1n, and g1d, including the new experimental information on the Q2 dependence of g1n. Careful attention is paid to the experimental and theoretical uncertainties. The data constrain the first moments of the polarized valence quark distributions, but only qualitatively constrain the polarized sea quark and gluon distributions. The NLO results are used to determine the Q2 dependence of the ratio g1F1 and evolve the experimental data to a constant Q2 = 5 GeV2. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.