On trace anomaly in 2+1 flavor QCD

TL;DR

This paper presents recent lattice QCD results on the trace anomaly at finite temperature using various improved staggered quark actions, comparing them with HRG and perturbative calculations to understand QCD thermodynamics.

Contribution

It provides updated lattice calculations of the trace anomaly in 2+1 flavor QCD across multiple lattice spacings and analyzes their dependence on scale setting methods.

Findings

Lattice results show good agreement with HRG at low temperatures.

Trace anomaly results vary with different scale setting procedures.

Comparison with perturbative results highlights the temperature range of QCD validity.

Abstract

We report on recent progress by the HotQCD collaboration in studying the trace anomaly at non-zero temperature in 2+1 flavor QCD on lattices with the temporal extent N_tau=4, 6, 8, 10 and 12 using the highly improved staggered quark (HISQ) action as well as the asqtad action. We discuss the dependence of our lattice results on the scale setting procedure and compare them with hadron resonance gas (HRG) calculations as well as to resummed perturbative results.