Phase structure of lattice QCD with two flavors of Wilson quarks at finite temperature and chemical potential

TL;DR

This paper investigates the phase structure of lattice QCD with two flavors of Wilson quarks at finite temperature and small chemical potential, using simulations at imaginary chemical potential and analytic continuation to real values.

Contribution

It provides new insights into the nature of phase transitions in lattice QCD at finite temperature and chemical potential, especially near the physical quark mass range.

Findings

Transition is first order in the infinite heavy quark limit.

No phase transition observed at intermediate quark masses.

Results obtained through analytic continuation from imaginary to real chemical potential.

Abstract

We present results for phase structure of lattice QCD with two degenerate flavors ($N_f=2$) of Wilson quarks at finite temperature $T$ and small baryon chemical potential $\mu_B$. Using the imaginary chemical potential for which the fermion determinant is positive, we perform simulations at points where the ratios of pseudo-scalar meson mass to the vector meson mass $m_\pi/m_\rho$ are between $0.943(3)$ and $0.899(4)$ as well as in the quenched limit. By analytic continuation to real quark chemical potential $\mu$, we obtain the transition temperature as a function of small $\mu_B$. We attempt to determine the nature of transition at imaginary chemical potential by histogram, MC history, and finite size scaling. In the infinite heavy quark limit, the transition is of first order. At intermediate values of quark mass $m_q$ corresponding to the ratio of $m_\pi/m_\rho$ in the range from $0.943(3)$ to $0.899(4)$ at $a\mu_I=0.24$, the MC simulations show absence of phase transition.