Study of the critical point in lattice QCD at high temperature and density

TL;DR

This paper investigates the nature of phase transitions in lattice QCD at high temperature and density by analyzing effective potentials, revealing a first order transition line at high density using simulations with improved staggered quarks.

Contribution

The study introduces a method based on effective potential analysis to identify phase transition types in lattice QCD at finite density, supported by simulation data.

Findings

First order phase transition line appears at high density for μ_q/T ≈ 2.5.

Effective potential analysis as a function of the average plaquette indicates transition nature.

Chemical potential as a function of density supports the existence of the first order transition line.

Abstract

We propose a method to probe the nature of phase transitions in lattice QCD at finite temperature and density, which is based on the investigation of an effective potential as a function of the average plaquette. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass $m/T = 0.4$, and find that a first order phase transition line appears in the high density regime for $\mu_q/T \sim 2.5$. The effective potential as a function of the quark number density is also studied. We calculate the chemical potential as a function of the density from the canonical partition function and discuss the existence of the first order phase transition line.