A worldline approach to colored particles

TL;DR

This paper develops a worldline approach using bosonic auxiliary variables to compute the one-loop gluon effective action, enabling projection onto specific gauge group representations, including symmetric and antisymmetric tensor products.

Contribution

It introduces a novel bosonic auxiliary variable method for projecting onto arbitrary irreducible representations in a worldline formalism for gauge theories.

Findings

Successfully projects onto fundamental, symmetric, and antisymmetric representations.

Provides a unified framework for different color charge configurations.

Enhances gauge invariance and computational efficiency in quantum field theory.

Abstract

Relativistic particle actions are a useful tool to describe quantum field theory effective actions using a string-inspired first-quantized approach. Here we describe how to employ suitable particle actions in the computation of the scalar contribution to the one-loop gluon effective action. We use the well-known method of introducing auxiliary variables that create the color degrees of freedom. In a path integral they implement automatically the path ordering needed to ensure gauge invariance. It is known that the color degrees of freedom introduced this way form a reducible representation of the gauge group. We describe a method of projecting onto the fundamental representation (or any other chosen irrep, if desired) of the gauge group. Previously, we have discussed the case of anticommuting auxiliary variables. Choosing them to be in the fundamental representation allows to obtain, without any extra effort, also the situation in which the color is given by any antisymmetric tensor product of the fundamental. Here, we describe the novel case of bosonic auxiliary variables. They can be used equivalently for creating the color charges in the fundamental representation. In addition one gets, as a byproduct, the cases where the particle can have the color sitting in any symmetric tensor product of the fundamental. This is obtained by tuning to a different value a Chern Simons coupling, present in the model, which controls how the projection is achieved.