Next-to-leading-order radiative parton model analysis of polarized deep inelastic lepton-nucleon scattering

A next-to-leading-order QCD analysis of spin asymmetries and structure functions in polarized deep inelastic lepton-nucleon scattering is presented within the framework of the radiative parton model. A consistent NLO formulation of the ${\mathit{Q}}^2$ evolution of polarized parton distributions yields two sets of plausible NLO spin-dependent parton distributions in the conventional MS factorization scheme. They respect the fundamental positivity constraints down to the low resolution scale ${\mathit{Q}}^2$=${\mathrm{\mu }}_{\mathrm{NLO}}^2$=0.34 ${\mathrm{GeV}}^2$. The ${\mathit{Q}}^2$ dependence of the spin asymmetries ${\mathit{A}}_1^{\mathit{p},\mathit{n},\mathit{d}}$(x,${\mathit{Q}}^2$) is similar to the leading-order (LO) one in the range 1≤${\mathit{Q}}^2$≤20 ${\mathrm{GeV}}^2$ and is shown to be non-negligible for x values relevant for the analysis of the present data and possibly forthcoming data at DESY HERA. © 1996 The American Physical Society.