Spectral Analysis of Gluonic Pole Matrix Elements

TL;DR

This paper investigates the spectral properties of quark-quark-gluon correlators using a spectator framework, revealing that gluonic pole contributions vanish in fragmentation functions, impacting their universality.

Contribution

It introduces a spectral analysis approach to gluonic pole matrix elements and demonstrates their non-contribution to fragmentation functions, advancing understanding of TMD factorization.

Findings

Gluonic pole matrix elements vanish in fragmentation functions.

Spectral properties of quark-quark-gluon correlators are characterized.

Implications for the universality of fragmentation functions.

Abstract

We use a spectator framework to investigate the spectral properties of quark-quark-gluon correlators and use this to study gluonic pole matrix elements. Such matrix elements appear in principle both for distribution functions such as the Sivers function and fragmentation functions such as the Collins function. We find that the contribution of the gluonic pole matrix element in fragmentation functions vanishes. This outcome is important in the study of universality for fragmentation functions.