DIMENSIONAL REDUCTION AND COLOR SCREENING IN QCD

We consider four flavour QCD in the high-temperature phase. Applying t he well-established method of dimensional reduction, we are able to st udy the quark potential both at short distances, where perturbation th eory is valid, as well as at large distances where screening sets in. This allows, for the first time, a determination of the screening mass in the quark-gluon plasma. We obtain at temperature T congruent-to 2. 5 T(c) for the Debye mass m(D)/T = 1.11(12), which is in good agreemen t with resummed infinite volume perturbation theory to leading order.