Equation of state at finite density in two-flavor QCD with improved Wilson quarks

TL;DR

This study investigates the equation of state in two-flavor QCD at finite temperature and density using improved Wilson quarks, computing derivatives of the quark determinant to explore thermodynamic properties and susceptibilities.

Contribution

It introduces a method to compute derivatives of the quark determinant at finite density with improved Wilson quarks, providing new insights into QCD thermodynamics.

Findings

Enhanced quark number susceptibility at finite chemical potential.

Evidence suggesting a nearby critical point in the phase diagram.

Consistent results with previous studies using staggered quarks.

Abstract

We study the equation of state in two-flavor QCD at finite temperature and density. Simulations are made with the RG-improved gluon action and the clover-improved Wilson quark action. Along the lines of constant physics for $m_{\rm PS}/m_{\rm V} = 0.65$ and 0.80, we compute the derivatives of the quark determinant with respect to the quark chemical potential $\mu_q$ up to the fourth order at $\mu_q=0$. We adopt several improvement techniques in the evaluation. We study thermodynamic quantities and quark number susceptibilities at finite $\mu_q$ using these derivatives. We find enhancement of the quark number susceptibility at finite $\mu_q$, in accordance with previous observations using staggered-type quarks. This suggests the existence of a nearby critical point.