Roles of the color antisymmetric ghost propagator in the infrared QCD

TL;DR

This paper investigates the role of color antisymmetric ghost propagators in infrared QCD, analyzing lattice simulations and vertex corrections to understand their impact on confinement criteria and effective couplings.

Contribution

It introduces a detailed analysis of color antisymmetric ghost contributions in lattice QCD and their influence on infrared behavior and confinement mechanisms.

Findings

Infrared ghost propagator not purely color diagonal.

Vertex corrections significantly affect the ghost and gluon propagators.

Lattice results show different infrared exponents for Landau gauge gluon propagators.

Abstract

The results of Coulomb gauge and Landau gauge lattice QCD simulation do not agree completely with continuum theory. There are indications that the ghost propagator in the infrared region is not purely color diagonal as in high energy region. After presenting lattice simulation of configurations produced with Kogut-Susskind fermion (MILC collaboration) and those with domain wall fermion (RBC/UKQCD collaboration), I investigate in triple gluon vertex and the ghost-gluon-ghost vertex how the square of the color antisymmetric ghost contributes. Then the effect of the vertex correction to the gluon propagator and the ghost propagator is investigated. Recent Dyson-Schwinger equation analysis suggests the ghost dressing function $G(0)=$ finite and no infrared enhancement or $\alpha_G=0$. But the ghost propagator renormalized by the loop containing a product of color antisymmetric ghost is expected to behave as $< c\bar c>_r =-\frac{G(q^2)}{q^2}$ with $G(q^2)\propto q^{-2(1+\alpha_G)}$ with $\alpha_G = 0.5$, if the fixed point scenario is valid. I interpret the $\alpha_G=0$ solution should contain a vertex correction. The infrared exponent of our lattice Landau gauge gluon propagator of the RBC/UKQCD is $\kappa=\alpha_G=-0.5$ and that of MILC is about -0.7. The implication for the Kugo-Ojima color confinement criterion, QCD effective coupling and the Slavnov identity are given.