On the Landau gauge ghost-gluon-vertex close to and in the conformal window

Author:

Fabian Zierler, Reinhard Alkofer

Keyword:

High Energy Physics - Phenomenology, High Energy Physics - Phenomenology (hep-ph), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th)

journal:

date:

2023-12-11 00:00:00

Abstract

The gauge-boson, ghost and fermion propagators as well as the gauge-boson--ghost vertex function are studied for SU(N), Sp(2N) and SO(N) gauge groups. We solve a set of coupled Dyson-Schwinger equations in Landau gauge for a variable, fractional number $N_f$ of massless fermions in the fundamental representation. For large $N_f$ we find a phase transition from a chirally broken into a chirally symmetric phase that is consistent with the behaviour expected inside the conformal window. Even in the presence of fermions the gauge-boson--ghost-vertex dressing remains small. In the conformal window this vertex shows the expected power law behaviour. It does not assume its tree-level value in the far infrared, but the respective dressing function is a constant greater than one.

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