Orbital angular momentum in the nucleons

TL;DR

This paper reviews the importance of orbital angular momentum of partons in nucleons, discussing its role in nucleon properties, asymmetries in spin physics, and recent debates on its definition and measurement.

Contribution

It provides a comprehensive summary of recent developments and debates regarding the definition and extraction of orbital angular momentum in nucleons.

Findings

Orbital angular momentum significantly influences nucleon properties.

Recent discussions focus on defining and measuring orbital angular momentum.

Understanding this quantity is crucial for nucleon internal structure studies.

Abstract

In the last decade, it has been realized that the orbital angular momentum of partons inside the nucleon plays a major role. It contributes significantly to nucleon properties and is at the origin of many asymmetries observed in spin physics. It is therefore of paramount importance to determine this quantity if we want to understand the nucleon internal structure and experimental observables. This triggered numerous discussions and controversies about the proper definition of orbital angular momentum and its extraction from experimental data. We summarize the present situation and discuss recent developments in this field.