Excitations of the static quark-antiquark system in several gauge theories

TL;DR

This study investigates the gluon spectrum around a static quark-antiquark pair across different gauge theories, revealing a transition from non-string behavior at small separations to string-like behavior at larger distances, with detailed energy level analysis.

Contribution

It provides the first detailed lattice simulation comparison of gluon excitations with effective string theory predictions across multiple gauge theories.

Findings

At small R, energy levels do not match string theory expectations.

At R > 2 fm, energy levels align with effective string behavior.

Energy spacings approach pi/R with some fine structure.

Abstract

The spectrum of gluons in the presence of a static quark-antiquark pair is studied using Monte Carlo simulations on anisotropic space-time lattices. For very small quark-antiquark separations R, the level orderings and approximate degeneracies disagree with the expectations from an effective string theory. As the quark-antiquark separation R increases, a dramatic rearrangement of the energies occurs, and above 2 fm, all of the levels studied show behavior consistent with an effective string description. The energy spacings are nearly pi/R, but a tantalizing fine structure remains. In addition to 4-dimensional SU(3) gauge theory, results from 3-dimensional SU(2) and compact U(1) gauge theories are also presented.