Is the ground state of Yang-Mills theory Coulombic?

TL;DR

This paper investigates the nature of the ground state in SU(2) Yang-Mills theory, finding that a Coulombic state better approximates the true ground state than a thin flux tube model, especially as the regulator is removed.

Contribution

It demonstrates that a Coulombic state has a higher overlap with the ground state than the flux tube model, suggesting the Coulomb state may be the true continuum ground state.

Findings

Coulombic states have increasing overlap with the ground state as the regulator is removed.

Flux tube models are poor descriptions due to UV artifacts from their infinitesimal thickness.

Coulomb states could represent the true ground state in the continuum limit.

Abstract

We study trial states modelling the heavy quark-antiquark ground state in SU(2) Yang-Mills theory. A state describing the flux tube between quarks as a thin string of glue is found to be a poor description of the continuum ground state; the infinitesimal thickness of the string leads to UV artifacts which suppress the overlap with the ground state. Contrastingly, a state which surrounds the quarks with non-abelian Coulomb fields is found to have a good overlap with the ground state for all charge separations. In fact, the overlap increases as the lattice regulator is removed. This opens up the possibility that the Coulomb state is the true ground state in the continuum limit.