Polarized Structure Functions: a Theoretical Update

TL;DR

This paper reviews recent theoretical and experimental advances in understanding polarized structure functions, focusing on their QCD implications and how data analysis can refine knowledge of nucleon spin structure.

Contribution

It provides a comprehensive update on polarized structure functions, analyzing recent data, theoretical methods, and their implications for polarized sum rules and nucleon spin content.

Findings

Recent experimental data on $g_1$ impact sum rule tests.

Analysis of $x$ and $Q^2$ dependence improves structure function extraction.

Data helps determine polarized parton distributions.

Abstract

We review recent developments in the theory and phenomenology of polarized structure functions. We summarize recent experimental data on the proton and deuteron structure function $g_1$, and their impact on the understanding of polarized sum rules. Specifically, we discuss how accurate measurements of the singlet and nonsinglet first moment of $g_1$ test perturbative and nonperturbative QCD, and critically examine the way these measurements are arrived at. We then discuss how the extraction of structure functions from the data can be improved by means of a theoretical analysis of their $x$ and $Q^2$ dependence, and how, conversely, experimental information on this dependence can be used to pin down the polarized parton content of the nucleon.