Worldline techniques and QCD observables

TL;DR

This paper explores the properties of gauge links in QCD, focusing on their renormalization and anomalous dimensions, and demonstrates the equivalence of different gauge choices in specific calculations of TMD PDFs.

Contribution

It provides a detailed analysis of gauge links and their renormalization properties in QCD, highlighting the equivalence of lightcone and covariant gauges for TMD PDFs.

Findings

One-loop anomalous dimension matches in lightcone and covariant gauges.

No uncanceled rapidity singularities in the analyzed gauge configurations.

Deeper insight into gauge link renormalization in QCD.

Abstract

This report attempts to capture the essential workings of gauge links (Wilson lines) inside gauge-invariant formulations of parton distribution functions in QCD and gain some deeper insight into their key (renormalization) properties. We show, in particular, that the one-loop anomalous dimension of the Cherednikov-Stefanis quark TMD PDF is in the lightcone gauge $A^+=0$, combined with the Mandelstam--Leibbrandt pole prescription, the same as that obtained in the special covariant gauge $a=-3$, leaving no uncanceled rapidity singularities.