Singular gauge potentials and the gluon condensate at zero temperature

TL;DR

This paper introduces a gauge-invariant cooling method in SU(2) lattice gauge theory that isolates vortex structures, revealing a potential gluon condensate contribution related to the gluon condensate at zero temperature.

Contribution

It presents a novel cooling procedure that separates gluon fields from vortex structures in a gauge-invariant manner, linking vortex textures to the gluon condensate.

Findings

Vortex textures reproduce lowest glueball states.

The vortex contribution defines a finite action density at T=0.

The vortex texture suggests a gluon condensate with mass dimension 4.

Abstract

We consider a new cooling procedure which separates gluon degrees of freedom from singular center vortices in SU(2) LGT in a gauge invariant way. Restricted by a cooling scale $\kappa^4/\sigma^2$ fixing the residual SO(3) gluonic action relative to the string tension, the procedure is RG invariant. In the limit $\kappa \to 0$ a pure Z(2) vortex texture is left. This {\it minimal} vortex content does not contribute to the string tension. It reproduces, however, the lowest glueball states. With an action density scaling like $a^4$ with $\beta$, it defines a finite contribution to the action density at T=0 in the continuum limit. We propose to interpret this a mass dimension 4 condensate related to the gluon condensate. Similarly, this vortex texture is revealed in the Landau gauge.