Probing nucleon spin structure in deep-inelastic scattering, proton-proton collisions and Drell-Yan processes

TL;DR

This paper reviews experimental results on the spin structure of nucleons from various fixed-target and collider experiments, covering longitudinal, transverse, and multi-dimensional aspects, prior to the Electron-Ion Collider era.

Contribution

It provides a comprehensive pedagogical summary of experimental findings on nucleon spin structure, including GPDs and TMDs, highlighting their roles in mapping nucleon internal dynamics.

Findings

Experimental data on nucleon spin from SLAC, Fermilab, Jefferson Lab, CERN, DESY, and RHIC.

Insights into GPDs and TMDs as tools for multi-dimensional nucleon imaging.

Recent results on spin-orbit correlations in nucleons.

Abstract

A pedagogical summary of current and past experimental results of spin-dependent nucleon structure prior to the arrival of the Electron-Ion Collider is attempted. After an introduction, results from fixed-target experiments at SLAC, Fermilab, Jefferson Lab, CERN and DESY and collider experiments from RHIC are presented, starting with the longitudinal spin structure of the nucleon, followed by generalized parton distributions (GPDs), which map the proton in transverse position space. The final part discusses transverse proton or parton spin and transverse parton momenta (TMDs), and their their (spin-orbit) correlations, which are addressed by a multitude of recent experimental results. The GPDs and TMDs provide complementary pathways to mapping multi-dimensional nucleon structure.