Next-To-Leading Order Analysis of Polarized and Unpolarized Structure Functions

Abstract

We present numerical solutions of the $Q^2$ evolution equations at next-to-leading order (NLO) for unpolarized and polarized parton distributions, in both the flavor non-singlet and singlet channels. The numerical method is based on a contour integration algorithm in complex-moment space, and, unlike most standard fitting techniques, is not restricted to the use of analytic moments of distributions. We also compute analytic continuations of the recently calculated singlet anomalous dimensions, needed for evolving polarized quark and gluon distributions at NLO. Using these we study the NLO effects on the $x$ dependence of the spin-dependent structure functions $g_1^p$ and $g_1^n$.