# Gluon Radiation from a Classical Point Particle

## TL;DR

This paper models gluon radiation from a classical point particle struck by an ultra-relativistic nucleus, extending electrodynamics to include gluon fields, and provides insights into initial conditions in high-energy collisions.

## Contribution

It generalizes classical electrodynamics to include gluon radiation from a classical particle, within the Color Glass Condensate framework, for the first time.

## Key findings

- Gluon rapidity distribution is roughly constant at high rapidities.
- Provides a classical computation of momentum and coordinates of the struck particle.
- Lays groundwork for initial conditions in high-energy collision models.

## Abstract

We consider an initially at rest colored particle which is struck by an ultra-relativistic nucleus. The particle is treated classically both with respect to its motion and its color charge. The nucleus is treated as a sheet of colored glass within the context of the Color Glass Condensate framework. We compute both the momentum and coordinates of the struck classical particle and the emitted radiation. Our computations generalize the classic electrodynamics computation of the radiation of an accelerated charged particle to include the radiation induced by the charged gluon field. This latter contribution adds to the classic electrodynamics result and produces a gluon rapidity distribution that is roughly constant as a function of rapidity at rapidities far from the fragmentation region of the struck particles. These computations may form the basis of a first principles treatment for the initial conditions for the evolution of matter produced in the fragmentation region of asymptotically high energy collisions.