We study the profiles of the flux tube between a static quark and an antiquark in quenched SU(2) lattice gauge theory at temperatures around the deconfinement phase transition. The physical width of the flux tube and the string tension have been determined from the transverse profiles and the q q ¯ potential, respectively. Exploiting the computational power of a GPU accelerator in our flux tube investigation, we achieve much higher statistics through which we can increase the signal to noise ratio of our observables in the simulation. This has allowed the investigation of larger lattices as well as larger separations between the quarks than in our previous work. The improved accuracy gives us better results for the width and the string tension. The physical width of the flux tube increases with the temperature up to around T c while keeping its increasing dependence on the q q ¯ separation. The string tension results are compared for two different sizes of the lattice. As the lattice becomes larger and finer together with the improved precision, the temperature dependent string tension tends to have a smaller value than the previous one.

We explore the profiles of the flux tube connecting a quark and an antiquark in high temperature SU(3) lattice gauge theory in close vicinity to the critical temperature of the phase transition. In this work, we consider the more realistic case of the flux tube with dynamical quarks, extending the previous study to SU(3) gauge group and making use of the Gradient flow method in smoothing procedure for noise reduction. The profiles of the chromoelectric and chromomagnetic field strengths in the flux tube have been measured from Polyakov loop-plaquette correlations using the highly improved staggered quark (HISQ) action on a lattice with temporal extent N τ = 8. We present preliminary results for distances up to 2.5 fm and temperatures up to 1.09T c .

Chromoelectric and chromomagnetic field and energy density distributions produced by a quark-antiquark pair have been investigated in the presence of dynamical fermions in the close vicinity to the deconfinement phase transition. In our lattice simulation we have used highly improved staggered quark action and tree level improved Symanzik gauge (HISQ/tree) action on the lattices of two different sizes, exploiting the Gradient flow method for noise reduction. We find that, in full QCD with dynamical quarks, the dynamical fermions widen the flux tube in a short separation range of about R = 1 fm, after which an hadronization takes place due to the suppression by the dynamical fermions. Energy density and width of the flux tube vanish at about R = 1.8 fm and R = 1.5 fm, respectively, at all temperatures. The present results also suggest that the flux tube structure still persists in the deconfined phase and it melts gradually after certain temperature value is reached above the critical temperature.

In this study, we explore the distribution of energy-momentum tensor around a static quark and an antiquark in SU(3) pure gauge theory at finite temperature. Double extrapolated transverse distributions on mid-plane of the flux tube have been presented for the first time at nonzero temperature. Also, we investigate the spatial distributions of the flux tube on the source plane obtaining from the stress tensor for several 𝑞 q separations and temperatures above and below the critical temperature. The resultant distributions show the detailed structure of the flux tube. Finally, we show the dependence of 𝐹 𝑠𝑡𝑟 𝑒𝑠𝑠 that is computed from the integral of the stress tensor on the distance between the quark and antiquark on a finer lattice.

In the deconfinement phase transition, we have analyzed the shape of the one end of the flux tube computed by HISQ configurations in full QCD with (2+1) flavors. The ratio of the longitudinal and transverse profile of the parallel chrome-electric field strength  revealed that the transverse profile becomes wider than the longitudinal profile when the temperature increases. Also, we found that the comparison, as a function of the distance between two quarks, likely shows melting distances of the flux tube. The melting distances are different for each temperature. They are R = 1.5 fm at T/Tc = 0.97 and R = 1.2 fm at above the critical temperatures T/Tc = 1.00, 1.03, 1.06 and 1.09.