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Flux-tube structure in finite temperature QCD

M. Baker, P. Cea, V. Chelnokov, L. Cosmai, A. Papa

TL;DR

The paper addresses how the static quark–antiquark potential $V(d) \sim -c/d + \sigma d$ and the related chromoelectric flux tube evolve with temperature in 2+1 flavor QCD. It uses a connected Wilson-loop plaquette correlator to extract the field and employs curl subtraction to isolate the nonperturbative flux; this enables direct measurement of the flux tube profile. The main result is that the flux tube persists through the chiral crossover with the effective string tension remaining near its zero-temperature value up to about T0 ~ 140 MeV and then decaying exponentially with temperature, while the flux-tube width decreases roughly as 1/T, indicating screening rather than disappearance. These findings provide quantitative insights into confinement dynamics in hot QCD and the role of screening in flux tube dissolution.

Abstract

We present a study of the structure of the chromoelectrical field created by a static quark-antiquark pair in lattice QCD with 2+1 flavours of dynamical quarks, where the quark masses are set to their physical values. The analysis covers a wide range of temperatures both above and below the chiral crossover, and explores varying quark-antiquark distances, with the aim of identifying signals of deconfinement and string breaking in the field structure. To this end we apply the zero-curl perturbative field subtraction method, developed in our earlier studies of pure gauge SU(3) theory and of full QCD at zero temperature.

Flux-tube structure in finite temperature QCD

TL;DR

The paper addresses how the static quark–antiquark potential and the related chromoelectric flux tube evolve with temperature in 2+1 flavor QCD. It uses a connected Wilson-loop plaquette correlator to extract the field and employs curl subtraction to isolate the nonperturbative flux; this enables direct measurement of the flux tube profile. The main result is that the flux tube persists through the chiral crossover with the effective string tension remaining near its zero-temperature value up to about T0 ~ 140 MeV and then decaying exponentially with temperature, while the flux-tube width decreases roughly as 1/T, indicating screening rather than disappearance. These findings provide quantitative insights into confinement dynamics in hot QCD and the role of screening in flux tube dissolution.

Abstract

We present a study of the structure of the chromoelectrical field created by a static quark-antiquark pair in lattice QCD with 2+1 flavours of dynamical quarks, where the quark masses are set to their physical values. The analysis covers a wide range of temperatures both above and below the chiral crossover, and explores varying quark-antiquark distances, with the aim of identifying signals of deconfinement and string breaking in the field structure. To this end we apply the zero-curl perturbative field subtraction method, developed in our earlier studies of pure gauge SU(3) theory and of full QCD at zero temperature.

Paper Structure

This paper contains 3 sections, 6 equations, 5 figures.

Table of Contents

  1. Introduction
  2. Lattice setup and numerical results
  3. Summary

Figures (5)

  • Figure 2: Scaling check at $T \simeq 205$ MeV and $d \simeq 0.963$ fm for the full longitudinal chromoelectric field $E_x$ (left) and its nonperturbative component $E_x^{\rm NP}$ (right).
  • Figure 3: The fields at $T \approx 43$ MeV, $d \approx 0.963$ fm: (top left) full longitudinal field profile, (top right) full transverse field profile, (bottom left) nonperturbative field profile, (bottom right) comparison of full and nonperturbative fields at midplane.
  • Figure 4: The fields at $T \approx 146$ MeV, $d \approx 0.963$ fm: (left) nonperturbative field profile, (right) comparison of full and nonperturbative fields at midplane.
  • Figure 5: The fields at $T \approx 205$ MeV, $d \approx 0.963$ fm: (left) nonperturbative field profile, (right) comparison of full and nonperturbative fields at midplane.
  • Figure 6: (left) Effective string tension evaluated at the midplane for inter-quark distance $d \simeq$ 0.963 fm as a function of temperature, with best-fit to Eq. (\ref{['6.12']}). (right) Flux-tube width at the same distance, with best-fit to Eq. (\ref{['6.18']}).