Canonical partition function and finite density phase transition in lattice QCD

TL;DR

This paper investigates the nature of the finite density phase transition in lattice QCD, proposing a method to compute the canonical partition function and analyzing simulation data to identify a first-order transition at low temperature.

Contribution

It introduces a new approach to calculate the canonical partition function in lattice QCD and applies it to analyze the phase transition at finite density.

Findings

Finite density phase transition at low temperature is first order.

Method to compute canonical partition function with fixed quark number.

Simulation results support the first-order transition hypothesis.

Abstract

We discuss the nature of the phase transition for lattice QCD at finite temperature and density. We propose a method to calculate the canonical partition function by fixing the total quark number introducing approximations allowed in the low density region. An effective potential as a function of the quark number density is discussed from the canonical partition function. We analyze data obtained in a simulation of two-flavor QCD using p4-improved staggered quarks with bare quark mass $m/T = 0.4$ on a $16^3 \times 4$ lattice. The results suggest that the finite density phase transition at low temperature is of first order.