Lattice QCD at finite temperature and density in the phase-quenched approximation

Abstract

QCD at a finite quark-number chemical potential $\mu$ has a complex fermion determinant, which precludes its study by standard lattice QCD simulations. We therefore simulate lattice QCD at finite $\mu$ in the phase-quenched approximation, replacing the fermion determinant with its magnitude. These simulations are used to study the finite temperature transition for small $\mu$,where the position and nature of this transition are expected to be unchanged by this approximation. We look for the expected critical endpoint for 3-flavour QCD. Here, it had been argued that the critical point at zero $\mu$ would become the critical endpoint at small $\mu$, for quark masses just above the critical mass. Our simulations indicate that this does not happen, and there is no such critical endpoint for small $\mu$. We discuss how we might adapt techniques used for imaginary $\mu$ to improve the signal/noise ratio and strengthen our conclusions, using results from relatively low statistics studies.

20 pages, Latex source, 6 postscript figures. Version modified for publication. Most changes made in the introduction and conclusions. One reference removed and a number of references added

References in corpus (8)

• The order of the quantum chromodynamics transition predicted by the standard model of particle physics
• Finite density QCD with a canonical approach
• The QCD Sign Problem for Small Chemical Potential
• Accelerating Staggered Fermion Dynamics with the Rational Hybrid Monte Carlo (RHMC) Algorithm
• Effective field theories for QCD with rooted staggered fermions
• Breakdown of staggered fermions at nonzero chemical potential
• The Approach to the Thermodynamic Limit in Lattice QCD at μ\neq0
• The RHMC algorithm for theories with unknown spectral bounds

Cited by in corpus (11)

• Canonical partition function and finite density phase transition in lattice QCD
• QCD Thermodynamics from the Lattice
• Phase diagram in the imaginary chemical potential region and extended Z3 symmetry
• Determination of QCD phase diagram from the imaginary chemical potential region
• QCD phase diagram at finite baryon and isospin chemical potentials
• Vector-type four-quark interaction and its impact on QCD phase structure
• Complex Langevin simulations and the QCD phase diagram: Recent developments
• Correlations among discontinuities in QCD phase diagram
• Average phase factor in the PNJL model
• Sign problem and phase quenching in finite-density QCD: models, holography, and lattice
• Nature of Roberge-Weiss transition end points for heavy quarks in $N_f=2$ lattice QCD with Wilson fermions