Intrinsic Width of the Flux Tube as a tool to explore confining mechanisms in Lattice Gauge Theories

TL;DR

This study investigates the intrinsic width of flux tubes in SU(2) gauge theory in (2+1) dimensions, revealing its potential as a physical scale to differentiate confining models and testing various theoretical descriptions of confinement.

Contribution

It introduces the intrinsic width as a new physical scale and compares multiple confining models, highlighting the dual superconductor model's partial success and limitations.

Findings

High-temperature data fit Ising-like model well

Lower-temperature data favor dual superconductor model

Intrinsic width helps distinguish confining mechanisms

Abstract

We study the profile of the flux tube in the SU(2) gauge model in (2 + 1) dimensions, with a particular attention to the so called "intrinsic width" which drives the exponential decay of the flux density at large transverse distances and represents a new physical scale of the model. This quantity is directly related to the confining mechanism which generates the flux tube and can be used to test its properties. We study a wide range of different values of lattice spacing, temperature and flux tube lengths and show that our data are precise enough to distinguish between different confining models. In particular we show that at high temperatures (just below the deconfinement transition) the data are perfectly described by an Ising-like effective model based on the Svetitsky-Yaffe mapping. At lower temperatures this approximation does not hold anymore. In this regime (which is the most interesting one from a physical point of view) we test several alternative proposals and show that the dual superconductor model is the one which better fits the data. However, this proposal is not fully satisfactory, because the values of the Ginzburg-Landau parameter extracted from the fits increase with the length of the flux tube, which is not a feature predicted by the model. This suggests that a more sophisticated model is needed to explain confinement in non-abelian gauge theories and, at the same time, that our data on the intrinsic width may be a powerful tool to benchmark these candidates.