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

Abstract

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 ${\mathit{Q}}^{2}$=${\mathrm{\ensuremath{\mu}}}_{\mathrm{NLO}}^{2}$=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\ensuremath{\le}${\mathit{Q}}^{2}$\ensuremath{\le}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. \textcopyright{} 1996 The American Physical Society.