Gribov copies and anomalous scaling

TL;DR

This paper explores how Gribov copies influence the infrared behavior of gauge theories, proposing a modified perturbation theory that incorporates nonlocal ghost generalization, leading to potential unparticle-like behavior and a nontrivial infrared fixed point.

Contribution

It introduces a nonlocal ghost modification in perturbation theory to account for Gribov copies, revealing a possible infrared fixed point and unparticle-like gauge boson behavior.

Findings

Emergence of a nontrivial infrared fixed point.

Gauge bosons exhibit unparticle-like behavior in the infrared.

Ghost dominance affects power counting in the confining regime.

Abstract

Nonperturbative and lattice methods indicate that Gribov copies modify the infrared behavior of gauge theories and cause a suppression of gluon propagation. We investigate whether this can be implemented in a modified perturbation theory. The minimal modification proceeds via a nonlocal generalization of the Fadeev-Popov ghost that automatically decouples from physical states. The expected scale invariance of the physics associated with Gribov copies leads to the emergence of a nontrivial infrared fixed point. For a range of a scaling exponent the gauge bosons exhibit unparticlelike behavior in the infrared. The confining regime of interest for QCD requires a larger scaling exponent, but then the severity of ghost dominance upsets naive power counting for the infrared scaling behavior of amplitudes.