Spin Structure of the Nucleon - Status and Recent Results

TL;DR

This paper reviews the progress in understanding the nucleon spin structure through polarization data from various experiments, highlighting recent high-precision results and their implications for nucleon spin components.

Contribution

It provides a comprehensive overview of current knowledge on nucleon spin structure, incorporating recent experimental data and discussing future research directions.

Findings

Detailed insights into polarized parton densities

Constraints on gluon contribution to nucleon spin

Analysis of spin structure functions g_1 and g_2

Abstract

After the initial discovery of the so-called "spin crisis in the parton model" in the 1980's, a large set of polarization data in deep inelastic lepton-nucleon scattering was collected at labs like SLAC, DESY and CERN. More recently, new high precision data at large x and in the resonance region have come from experiments at Jefferson Lab. These data, in combination with the earlier ones, allow us to study in detail the polarized parton densities, the Q^2 dependence of various moments of spin structure functions, the duality between deep inelastic and resonance data, and the nucleon structure in the valence quark region. Together with complementary data from HERMES, RHIC and COMPASS, we can put new limits on the flavor decomposition and the gluon contribution to the nucleon spin. In this report, we provide an overview of our present knowledge of the nucleon spin structure and give an outlook on future experiments. We focus in particular on the spin structure functions g_1 and g_2 of the nucleon and their moments.