Lattice QCD at finite temperature and density in the phase-quenched approximation.
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. (The phase-quenched approximation can be considered as simulating at finite isospin chemical potential 2{mu} for N{sub f}/2 u-type and N{sub F}/2 d-type quark flavors.) These simulations are used to study the finite-temperature transition for small {mu}, where there is some evidence that the position (and possibly the nature) of this transition is unchanged by this approximation. We look for the expected critical endpoint for 3-flavor QCD. Here, it has 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.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); National Science Foundation (NSF); NRAC grant
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 935663
- Report Number(s):
- ANL-HEP-PR-07-81; TRN: US0804610
- Journal Information:
- Phys. Rev. D, Vol. 77, Issue Jun. 2008; ISSN 1550-7998
- Country of Publication:
- United States
- Language:
- ENGLISH
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