Next-to-Leading Order QCD Analysis of Polarized Deep Inelastic Scattering Data

We present a Next-to-Leading order perturbative QCD analysis of world data on the spin dependent structure functions $g_1^p, g_1^n$, and $g_1^d$, including the new experimental information on the $Q^2$ dependence of $g_1^n$. 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 $Q^2$ dependence of the ratio $g_1/F_1$ and evolve the experimental data to a constant $Q^2 = 5 GeV^2$. We determine the first moments of the polarized structure functions of the proton and neutron and find agreement with the Bjorken sum rule.Comment: 21 pages, 4 figures; final version to be published in Phys. Lett. B. References updated. Uses elsart.cls version 1996/04/22, 2e-1.4

Measurement of the neutron spin structure function g2ng_{2}^{n} and asymmetry a2na_{2}^{n}

We have measured the neutron structure function g2n_{2}^{n}2n​ and the virtual photon-nucleon asymmetry A2n_{2}^{n}2n​ over the kinematic range 0.014≤x≤0.70.014\leq x \leq 0.70.014≤x≤0.7 and 1.0≤Q2≤17.01.0 \leq Q^{2} \leq 17.01.0≤Q2≤17.0 by scattering 48.3 GeV longitudinally polarized electrons from polarized 3^{3}3He. Results for A2n_{2}^{n}2n​ are significantly smaller than the R\sqrt{R}R​ positivity limit over most of the measured range and data for g2n_2^{n}2n​ are generally consistent with the twist-2 Wandzura-Wilczek prediction. Using our measured g2n_{2}^{n}2n​ we obtain results for the twist-3 reduced matrix element d2nd_{2}^{n}d2n​, and the integral ∫\int∫g2n(x)dx_{2}^{n}(x)dx2n​(x)dx in the range 0.014≤x≤1.00.014\leq x \leq 1.00.014≤x≤1.0. Data from this experiment are combined with existing data for g2n_{2}^{n}2n​ to obtain an average for d2nd_{2}^{n}d2n​ and the integral ∫\int∫g2n(x)dx_{2}^{n}(x)dx2n​(x)dx