Non-Abelian Debye screening: The color-averaged potential

Open-boundary conditions in the deconfined phase

In this work, we consider open-boundary conditions at high temperatures, as they can potentially be of help to measure the topological susceptibility. In particular, we measure the extent of the boundary effects at T = 1.5 T c and T = 2.7 T c . In the first case, it is larger than at T = 0 while we find it to be smaller in the second case. The length of this "boundary zone" is controlled by the screening masses. We use this fact to measure the scalar and pseudo-scalar screening masses at these two temperatures. We observe a mass gap at T = 1.5 T c but not at T = 2.7 T c . Finally, we use our pseudo-scalar channel analysis to estimate the topological susceptibility. The results at T = 1.5 T c are in good agreement with the literature. At T = 2.7 T c , they appear to suffer from topological freezing, which prevents us from providing a precise determination of the topological susceptibility.

Fermions obstruct dimensional reduction in hot QCD

We have studied, for the first time, screening masses obtained from glueball-like correlators in quantum chromodynamics with four light dynamical flavors of quarks in the temperature range 1. 5T(c)</=T</=3T(c), where T(c) is the temperature at which the chiral transition occurs. We have also studied pionlike and sigmalike screening masses and found that they are degenerate in the entire range of T. These obstruct perturbative dimensional reduction since the lowest glueball screening mass is heavier than them. Extrapolation of our results suggests that this obstruction may affect the entire range of temperature expected to be reached even at the Large Hadron Collider.