Gluon mass through ghost synergy

TL;DR

This paper investigates the nonperturbative role of ghost loops in the gluon propagator within the PT-BFM formalism, demonstrating their crucial contribution to the dynamical generation of gluon mass and aligning with lattice data.

Contribution

It provides a one-loop-dressed calculation of ghost contributions to the gluon self-energy using the PT-BFM framework, linking ghost effects to gluon mass generation.

Findings

Ghost loops significantly affect the gluon propagator shape.

Removing ghost loops causes the gluon mass to vanish.

Ghost and gluon effects are deeply interconnected in mass generation.

Abstract

In this work we compute, at the "one-loop-dressed" level, the nonperturbative contribution of the ghost loops to the self-energy of the gluon propagator, in the Landau gauge. This is accomplished within the PT-BFM formalism, which guarantees the gauge-invariance of the emerging answer. In particular, the contribution of the ghost-loops is automatically transverse, by virtue of the QED-like Ward identities satisfied in this framework. Using as nonperturbative input the available lattice data for the ghost dressing function, we show that the ghost contributions have a rather sizable effect on the overall shape of the gluon propagator, both for $d=3,4$. Then, by exploiting a recently introduced dynamical equation for the effective gluon mass, whose solutions depend crucially on the characteristics of the gluon propagator at intermediate energies, we show that if the ghost loops are removed from the gluon propagator then the gluon mass vanishes. These findings strongly suggest that, at least at the level of the Schwinger-Dyson equations, the effects of gluons and ghosts are inextricably connected, and must be combined suitably in order to reproduce the results obtained in the recent lattice simulations.