PERTURBATIVE VERSUS LATTICE QCD ENERGY DENSITY CORRELATORS AT HIGH-TEMPERATURES

Correlators of magnetic and electric field energy density are investig ated for SU(N-c) gauge theory at high temperatures T. At separations z less than or equal to 2/T the correlators are shown to be dominated b y a power-law behavior even for finite gluon screening masses. This co ntinuum behavior is well approximated on current 4 x 16(3)-lattices in the perturbative limit and leads to a considerable overestimate of sc reening masses deduced from fitting the lattice correlators with conve ntional exponential forms. The use of extended sources and sinks to en hance the signal improves the situation for screening masses m much gr eater than T but leads to a largely uncontrolled error for masses less than T. In fact, we show that recent lattice QCD data of Grossmann et al., from which a magnetic screening mass m(M) approximate to 2.9 T w as deduced, may even be consistent with a vanishing actual magnetic sc reening mass.