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Complex Langevin calculations in QCD at finite density

Yuta Ito
(
- KEK, Tsukuba and
- Tokuyama Women's Coll.
)
,
Hideo Matsufuru
(
- KEK, Tsukuba
)
,
Yusuke Namekawa
(
- KEK, Tsukuba
)
,
Jun Nishimura
(
- KEK, Tsukuba and
- Sokendai, Tsukuba
)
,
Shinji Shimasaki
(
- Keio U.
)

Jul 17, 2020

19 pages

Published in:

JHEP 10 (2020) 144

Published: Oct 22, 2020

e-Print:

2007.08778 [hep-lat]

DOI:

10.1007/JHEP10(2020)144

Report number:

KEK-TH-2230,
RIKEN-QHP-479

View in:

ADS Abstract Service

reference search28 citations

Citations per year

Abstract: (Springer)

We demonstrate that the complex Langevin method (CLM) enables calculations in QCD at finite density in a parameter regime in which conventional methods, such as the density of states method and the Taylor expansion method, are not applicable due to the severe sign problem. Here we use the plaquette gauge action with β = 5.7 and four-flavor staggered fermions with degenerate quark mass ma = 0.01 and nonzero quark chemical potential μ. We confirm that a sufficient condition for correct convergence is satisfied for μ/T = 5.2 − 7.2 on a 8

^{3}

× 16 lattice and μ/T = 1.6 − 9.6 on a 16

^{3}

× 32 lattice. In particular, the expectation value of the quark number is found to have a plateau with respect to μ with the height of 24 for both lattices. This plateau can be understood from the Fermi distribution of quarks, and its height coincides with the degrees of freedom of a single quark with zero momentum, which is 3 (color) × 4 (flavor) × 2 (spin) = 24. Our results may be viewed as the first step towards the formation of the Fermi sphere, which plays a crucial role in color superconductivity conjectured from effective theories.

Note:

17 pages, 4 figures; published version

Lattice QCD
Phase Diagram of QCD
density: finite
quark: mass
color: superconductivity
potential: chemical
fermion: staggered
lattice
quantum chromodynamics
Taylor expansion

References(60)

Figures(11)

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(
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(
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)
,
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)
,
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(
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)
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Shoichiro Tsutsui
(
- KEK, Tsukuba
)
,
Yuta Ito
(
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)
,
Hideo Matsufuru
(
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)
,
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(
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Shoichiro Tsutsui
(
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,
Yuta Ito
(
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)
,
Hideo Matsufuru
(
- KEK, Tsukuba
)
,
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(
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)
,
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J.B. Kogut
(
- Dept. of Energy, Wash., D.C. and
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)
,
D.K. Sinclair
(
- Argonne
)

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D.K. Sinclair
(
- Argonne
)
,
J.B. Kogut
(
- Dept. of Energy, Wash., D.C. and
- Maryland U.
)

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Shoichiro Tsutsui
(
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,
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,
Hideo Matsufuru
(
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)
,
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M. Scherzer
(
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,
D. Sexty
(
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)
,
I.O. Stamatescu
(
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(
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(
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Gert Aarts
(
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,
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(
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)
,
Erhard Seiler
(
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)
,
Ion-Olimpiu Stamatescu
(
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Jun Nishimura
(
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)
,
Shinji Shimasaki
(
- KEK, Tsukuba
)

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•
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Keitaro Nagata
(
- KEK, Tsukuba
)
,
Jun Nishimura
(
- KEK, Tsukuba and
- Sokendai, Tsukuba
)
,
Shinji Shimasaki
(
- KEK, Tsukuba
)

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Keitaro Nagata
(
- KEK, Tsukuba
)
,
Jun Nishimura
(
- KEK, Tsukuba and
- Sokendai, Tsukuba
)
,
Shinji Shimasaki
(
- Keio U. and
- KEK, Tsukuba
)

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•
e-Print:
- 1606.07627
•
DOI:
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[25]

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L.L. Salcedo
(
- Granada U.
)

- Phys.Rev.D 94 (2016) 11, 114505
•
e-Print:
- 1611.06390
•
DOI:
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