QCD trace anomaly

In this brief report we compare the predictions of a recent next-to-next-to-leading order hard-thermal-loop perturbation theory (HTLpt) calculation of the QCD trace anomaly to available lattice data. We focus on the trace anomaly scaled by T-2 in two cases: N-f = 0 and N-f = 3. When using the canonical value of mu = 2 pi T for the renormalization scale, we find that for Yang-Mills theory (N-f = 0) agreement between HTLpt and lattice data for the T-2-scaled trace anomaly begins at temperatures on the order of 8T(c), while when including quarks (N-f = 3) agreement begins already at temperatures above 2T(c). In both cases we find that at very high temperatures the T-2-scaled trace anomaly increases with temperature in accordance with the predictions of HTLpt.