Quark number susceptibilities at high temperatures

TL;DR

This paper computes second and fourth order quark number susceptibilities in high-temperature QCD using improved lattice formulations, comparing results with weak coupling calculations to understand quark behavior in extreme conditions.

Contribution

It provides a detailed lattice QCD calculation of quark number susceptibilities at high temperatures using multiple improved fermion formulations, and compares these with weak coupling predictions.

Findings

Second order susceptibilities are consistent across formulations in the continuum limit.

Fourth order susceptibilities agree reasonably with weak coupling calculations at finite lattice spacings.

The study enhances understanding of quark behavior at high temperatures in QCD.

Abstract

We calculate second and fourth order quark number susceptibilities for 2+1 flavor QCD in the high temperature region. In our study we use two improved staggered fermion formulations, namely the highly improved staggered quark formulation, and the so-called p4 formulation, as well as several lattice spacings. Second order quark number susceptibilities are calculated using both improved staggered fermion formulations, and we show that in the continuum limit the two formulations give consistent results. The fourth order quark number susceptibilities are studied only using the p4 formulation and at non-zero lattice spacings. We compare our results on quark number susceptibilities with recent weak coupling calculations, and find that these agree reasonably well with the lattice calculations within the estimated uncertainties.