Three-point vertex functions in Yang-Mills Theory and QCD in Landau gauge

TL;DR

This paper investigates the nonperturbative three-point vertex functions in Yang-Mills theory and QCD within Landau gauge, focusing on how dynamical quarks influence the three-gluon and quark-gluon vertices through Dyson-Schwinger equations.

Contribution

It provides a detailed analysis of the impact of unquenching on three-gluon and quark-gluon vertices using Dyson-Schwinger equations and the three-particle irreducible formalism, highlighting the minor role of certain diagrams.

Findings

Unquenching shifts the three-gluon vertex dressing function towards the infrared.

The quark-swordfish diagram has minor influence in the studied model.

Dynamical quarks modify the three-gluon vertex via quark-triangle diagrams.

Abstract

Solutions for the three-gluon and quark-gluon vertices from Dyson-Schwinger equations and the three-particle irreducible formalism are discussed. Dynamical quarks (``unquenching'') change the three-gluon vertex via the quark-triangle diagrams which themselves include fully dressed quark-gluon vertex functions. On the other hand, the quark-swordfish diagram is, at least with the model used for the two-quark-two-gluon vertex employed here, of minor importance. For the leading tensor structure of the three-gluon vertex the "unquenching" effect can be summarized for the nonperturbative part as a shift of the related dressing function towards the infrared.