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 T² in two cases: Nf=0 and Nf=3. When using the canonical value of μ=2πT for the renormalization scale, we find that for Yang-Mills theory (Nf=0) agreement between HTLpt and lattice data for the T²-scaled trace anomaly begins at temperatures on the order of 8Tc, while when including quarks (Nf=3) agreement begins already at temperatures above 2Tc. In both cases we find that at very high temperatures the T²-scaled trace anomaly increases with temperature in accordance with the predictions of HTLpt.