Heavy quark potentials in quenched QCD at high temperature

Heavy quark potentials are investigated at high temperatures. The temperature range covered by the analysis extends from $T$ values just below the deconfinement temperature up to about ${4T}_c$ in the deconfined phase. We simulated the pure gauge sector of QCD on lattices with temporal extents of 4, 6, and 8, with spatial volumes of ${32}^3.$ On the smallest lattice a tree level improved action was employed, while in the other two cases the standard Wilson action was used. Below $T_c$ we find a temperature-dependent logarithmic term contributing to the confinement potential, and observe a string tension which decreases with rising temperature but retains a finite value at the deconfinement transition. Above $T_c$ the potential is Debye screened; however, simple perturbative predictions do not apply.