Infrared exponents and the strong-coupling limit in lattice Landau gauge

TL;DR

This study investigates the infrared behavior of gluon and ghost propagators in lattice Landau gauge at strong coupling, revealing conformal behavior consistent with continuum predictions and highlighting the effects of lattice definitions and finite-volume considerations.

Contribution

It provides evidence of conformal infrared behavior in lattice Landau gauge at strong coupling and clarifies the influence of lattice definitions and finite-volume effects on these propagators.

Findings

Conformal infrared behavior observed at strong coupling

Deviations characterized by a transverse gluon mass

Deviations depend on lattice gauge field definitions

Abstract

We study the gluon and ghost propagators of lattice Landau gauge in the strong-coupling limit beta=0 in pure SU(2) lattice gauge theory to find evidence of the conformal infrared behavior of these propagators as predicted by a variety of functional continuum methods for asymptotically small momenta $q^2 \ll \Lambda_\mathrm{QCD}^2$. In the strong-coupling limit, this same behavior is obtained for the larger values of a^2q^2 (in units of the lattice spacing a), where it is otherwise swamped by the gauge field dynamics. Deviations for a^2q^2 < 1 are well parameterized by a transverse gluon mass $\propto 1/a$. Perhaps unexpectedly, these deviations are thus no finite-volume effect but persist in the infinite-volume limit. They furthermore depend on the definition of gauge fields on the lattice, while the asymptotic conformal behavior does not. We also comment on a misinterpretation of our results by Cucchieri and Mendes in Phys. Rev. D81 (2010) 016005.