Lattice study on finite density QC2D towards zero temperature

Abstract We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC2D) at low temperature (T = 40 MeV, 324 lattice) for the purpose of extending our previous works [1, 2] at T = 80 MeV (164 lattice). Indeed, a rich phase structure below the pseudo-critical tempera...

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Main Authors: Kei Iida, Etsuko Itou, Kotaro Murakami, Daiki Suenaga
Format: Article
Language:English
Published: SpringerOpen 2024-10-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP10(2024)022
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author Kei Iida
Etsuko Itou
Kotaro Murakami
Daiki Suenaga
author_facet Kei Iida
Etsuko Itou
Kotaro Murakami
Daiki Suenaga
author_sort Kei Iida
collection DOAJ
description Abstract We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC2D) at low temperature (T = 40 MeV, 324 lattice) for the purpose of extending our previous works [1, 2] at T = 80 MeV (164 lattice). Indeed, a rich phase structure below the pseudo-critical temperature T c as a function of quark chemical potential μ has been revealed, but finite volume effects in a high-density regime sometimes cause a wrong understanding. Therefore, it is important to investigate the temperature dependence down to zero temperature with large-volume simulations. By performing 324 simulations, we obtain essentially similar results to the previous ones, but we are now allowed to get a fine understanding of the phase structure via the temperature dependence. Most importantly, we find that the hadronic-matter phase, which is composed of thermally excited hadrons, shrinks with decreasing temperature and that the diquark condensate scales as ⟨qq⟩ ∝ μ 2 in the BCS phase, a property missing at T = 80 MeV. From careful analyses, furthermore, we confirm a tentative conclusion that the topological susceptibility is independent of μ. We also show the temperature dependence of the pressure, internal energy, and sound velocity as a function of μ. The pressure increases around the hadronic-superfluid phase transition more rapidly at the lower temperature, while the temperature dependence of the sound velocity is invisible. Breaking of the conformal bound is also confirmed thanks to the smaller statistical error.
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spelling doaj-art-8cd674f3fd424a9ebba49a07981b2e0a2025-08-20T02:20:37ZengSpringerOpenJournal of High Energy Physics1029-84792024-10-0120241012910.1007/JHEP10(2024)022Lattice study on finite density QC2D towards zero temperatureKei Iida0Etsuko Itou1Kotaro Murakami2Daiki Suenaga3Department of Mathematics and Physics, Kochi UniversityYukawa Institute for Theoretical Physics, Kyoto UniversityInterdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS), RIKENKobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya UniversityAbstract We investigate the phase structure and the equation of state (EoS) for dense two-color QCD (QC2D) at low temperature (T = 40 MeV, 324 lattice) for the purpose of extending our previous works [1, 2] at T = 80 MeV (164 lattice). Indeed, a rich phase structure below the pseudo-critical temperature T c as a function of quark chemical potential μ has been revealed, but finite volume effects in a high-density regime sometimes cause a wrong understanding. Therefore, it is important to investigate the temperature dependence down to zero temperature with large-volume simulations. By performing 324 simulations, we obtain essentially similar results to the previous ones, but we are now allowed to get a fine understanding of the phase structure via the temperature dependence. Most importantly, we find that the hadronic-matter phase, which is composed of thermally excited hadrons, shrinks with decreasing temperature and that the diquark condensate scales as ⟨qq⟩ ∝ μ 2 in the BCS phase, a property missing at T = 80 MeV. From careful analyses, furthermore, we confirm a tentative conclusion that the topological susceptibility is independent of μ. We also show the temperature dependence of the pressure, internal energy, and sound velocity as a function of μ. The pressure increases around the hadronic-superfluid phase transition more rapidly at the lower temperature, while the temperature dependence of the sound velocity is invisible. Breaking of the conformal bound is also confirmed thanks to the smaller statistical error.https://doi.org/10.1007/JHEP10(2024)022Non-Zero Temperature and DensityOther Lattice Field TheoriesPhase Transitions
spellingShingle Kei Iida
Etsuko Itou
Kotaro Murakami
Daiki Suenaga
Lattice study on finite density QC2D towards zero temperature
Journal of High Energy Physics
Non-Zero Temperature and Density
Other Lattice Field Theories
Phase Transitions
title Lattice study on finite density QC2D towards zero temperature
title_full Lattice study on finite density QC2D towards zero temperature
title_fullStr Lattice study on finite density QC2D towards zero temperature
title_full_unstemmed Lattice study on finite density QC2D towards zero temperature
title_short Lattice study on finite density QC2D towards zero temperature
title_sort lattice study on finite density qc2d towards zero temperature
topic Non-Zero Temperature and Density
Other Lattice Field Theories
Phase Transitions
url https://doi.org/10.1007/JHEP10(2024)022
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AT etsukoitou latticestudyonfinitedensityqc2dtowardszerotemperature
AT kotaromurakami latticestudyonfinitedensityqc2dtowardszerotemperature
AT daikisuenaga latticestudyonfinitedensityqc2dtowardszerotemperature