Fixed Scale Approach to Equation of State in Lattice QCD

TL;DR

This paper introduces a novel lattice QCD method where temperature variation is achieved by changing lattice size at fixed scale, enabling more reliable calculations of the QCD equation of state, especially at lower temperatures.

Contribution

The paper proposes the $T$-integral method, a new approach to study the QCD equation of state by varying temperature through lattice size at fixed scale, differing from traditional fixed-$N_t$ methods.

Findings

The $T$-integral method produces reliable results at intermediate and low temperatures.

The approach is validated in quenched QCD on isotropic and anisotropic lattices.

It offers an alternative to conventional methods for calculating the QCD equation of state.

Abstract

A new approach to study the equation of state in finite-temperature QCD is proposed on the lattice. Unlike the conventional method in which the temporal lattice size $N_t$ is fixed, the temperature $T$ is varied by changing $N_t$ at fixed lattice scale. The pressure of the hot QCD plasma is calculated by the integration of the trace anomaly with respect to $T$ at fixed lattice scale. This "$T$-integral method" is tested in quenched QCD on isotropic and anisotropic lattices and is shown to give reliable results especially at intermediate and low temperatures.