Study of QCD thermodynamics at finite density by Taylor expansion

TL;DR

This paper investigates the phase structure and thermodynamics of QCD at finite density using Taylor expansion techniques, providing insights into the equation of state and critical points at non-zero temperature and chemical potential.

Contribution

It introduces a method to estimate QCD thermodynamic quantities at finite density by calculating derivatives of the partition function up to fourth order, advancing the understanding of the phase diagram.

Findings

Estimates of pressure, quark number density, and susceptibilities as functions of chemical potential.

Identification of the phase transition line for 2 and 3-flavor QCD.

Locating the critical endpoint in the temperature-chemical potential plane.

Abstract

We discuss the phase structure and the equation of state for QCD at non-zero temperature and density. Derivatives of $\ln Z$ with respect to quark chemical potential $\mu_q$ up to fourth order are calculated for 2-flavor QCD, enabling estimates of the pressure, quark number density and associated susceptibilities as functions of $\mu_q$ via a Taylor series expansion. Also, the phase transition line for 2 and 3-flavor QCD and the critical endpoint in the $(T, \mu_q)$ plane are investigated in the low density regime.