# Contribution of Orbital Angular Momentum to the Nucleon Spin

## TL;DR

This paper calculates the orbital angular momentum contributions of quarks and gluons to the nucleon spin using the valon model at next-to-leading order, revealing small positive quark and large negative gluon contributions.

## Contribution

It provides the first detailed calculation of quark and gluon orbital angular momentum in the nucleon at NLO within the valon model, including their Q^2 dependence.

## Key findings

- Quark orbital angular momentum is positive but small.
- Gluon orbital angular momentum is negative and large.
- Partonic angular momentum varies with Q^2.

## Abstract

We have calculated the Orbital Angular Momentum of quarks and gluons in the nucleon. The calculations are carried out in the next to leading order utilizing the so-called valon model. It is found that the average quark orbital angular momentum is positive, but small, and the average gluon orbital angular momentum is negative and large. We also report on some regularities about the total angular momentum of the quarks and the gluon, as well as on the orbital angular momentum of the separate partons. We have also provided partonic angular momentum, $L^{q,g}$ as a function of $Q^2$.