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Title: Applying complex Langevin simulations to lattice QCD at finite density

Abstract

We study the use of the complex-Langevin equation (CLE) to simulate lattice QCD at a finite chemical potential (μ) for a quark-number, which has a complex fermion determinant that prevents the use of standard simulation methods based on importance sampling. Recent enhancements to the CLE specific to lattice QCD inhibit runaway solutions which had foiled earlier attempts to use it for such simulations. However, it is not guaranteed to produce correct results. Our goal is to determine under what conditions the CLE yields correct values for the observables of interest. Zero temperature simulations indicate that for moderate couplings, good agreement with expected results is obtained for small μ and for μ large enough to reach saturation, and that this agreement improves as we go to weaker coupling. For intermediate μ values these simulations do not produce the correct physics. We compare our results with those of the phase-quenched approximation. Since there are indications that correct results might be obtained if the CLE trajectories remain close to the SU(3) manifold, we study how the distance from this manifold depends on the quark mass and on the coupling. We find that this distance decreases with decreasing quark mass and as the couplingmore » decreases, i.e., as the simulations approach the continuum limit.« less

Authors:
;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1566268
Alternate Identifier(s):
OSTI ID: 1577678
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Published Article
Journal Name:
Physical Review D
Additional Journal Information:
Journal Name: Physical Review D Journal Volume: 100 Journal Issue: 5; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics; Physics; Lattice QCD

Citation Formats

Kogut, J. B., and Sinclair, D. K. Applying complex Langevin simulations to lattice QCD at finite density. United States: N. p., 2019. Web. doi:10.1103/PhysRevD.100.054512.
Kogut, J. B., & Sinclair, D. K. Applying complex Langevin simulations to lattice QCD at finite density. United States. https://doi.org/10.1103/PhysRevD.100.054512
Kogut, J. B., and Sinclair, D. K. Wed . "Applying complex Langevin simulations to lattice QCD at finite density". United States. https://doi.org/10.1103/PhysRevD.100.054512.
@article{osti_1566268,
title = {Applying complex Langevin simulations to lattice QCD at finite density},
author = {Kogut, J. B. and Sinclair, D. K.},
abstractNote = {We study the use of the complex-Langevin equation (CLE) to simulate lattice QCD at a finite chemical potential (μ) for a quark-number, which has a complex fermion determinant that prevents the use of standard simulation methods based on importance sampling. Recent enhancements to the CLE specific to lattice QCD inhibit runaway solutions which had foiled earlier attempts to use it for such simulations. However, it is not guaranteed to produce correct results. Our goal is to determine under what conditions the CLE yields correct values for the observables of interest. Zero temperature simulations indicate that for moderate couplings, good agreement with expected results is obtained for small μ and for μ large enough to reach saturation, and that this agreement improves as we go to weaker coupling. For intermediate μ values these simulations do not produce the correct physics. We compare our results with those of the phase-quenched approximation. Since there are indications that correct results might be obtained if the CLE trajectories remain close to the SU(3) manifold, we study how the distance from this manifold depends on the quark mass and on the coupling. We find that this distance decreases with decreasing quark mass and as the coupling decreases, i.e., as the simulations approach the continuum limit.},
doi = {10.1103/PhysRevD.100.054512},
journal = {Physical Review D},
number = 5,
volume = 100,
place = {United States},
year = {2019},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
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https://doi.org/10.1103/PhysRevD.100.054512

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