QCD Analysis of Polarized Deep Inelastic Scattering Data

A QCD analysis of the world data on inclusive polarized deep inelastic scattering of leptons on nucleons is presented in leading and next-to-leading order. New parameterizations are derived for the quark and gluon distributions and the value of $\alpha_s(M_Z)$ is determined. Emphasis is put on the derivation of fully correlated error bands for these distributions which are directly applicable to determine experimental errors of other polarized observables. The impact of the variation of both the renormalization and factorization scales on the value of $\alpha_s$ is studied. Finally a factorization-scheme invariant QCD analysis based on the observables $g_1(x,Q^2)$ and $d g_1(x,Q^2)/d \log(Q^2)$ is performed in next-to-leading order, which is compared to the standard analysis.