Fluctuations and correlations in high temperature QCD

TL;DR

This paper computes higher-order cumulants of conserved charges in high-temperature QCD using lattice simulations, comparing results with Hadron Resonance Gas and perturbative models across a wide temperature range.

Contribution

It provides detailed lattice QCD calculations of cumulants from the transition region to perturbative regimes, validating models in different phases.

Findings

Hadron Resonance Gas model matches lattice data in the confined phase.

Agreement with three-loop Hard Thermal Loop results at high temperatures.

Continuum extrapolation performed with multiple lattice spacings.

Abstract

We calculate second- and fourth-order cumulants of conserved charges in a temperature range stretching from the QCD transition region towards the realm of (resummed) perturbation theory. We perform lattice simulations with staggered quarks; the continuum extrapolation is based on $N_t=10\dots24$ in the crossover-region and $N_t=8\dots16$ at higher temperatures. We find that the Hadron Resonance Gas model predictions describe the lattice data rather well in the confined phase. At high temperatures (above $\sim$250 MeV) we find agreement with the three-loop Hard Thermal Loop results.