The mixed phase quark core in massive hybrid stars

Abstract We investigate the properties of hybrid star and the mixed phase core to explore the radius ratio of the mixed phase in hybrid star. In the context of observed massive neutron stars (NSs), we examine the internal structure, phase transitions, and the impacts of the equation of state (EOS) i...

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Main Authors: Xuhao Wu, Peng-Cheng Chu, Min Ju, He Liu
Format: Article
Language:English
Published: SpringerOpen 2025-03-01
Series:European Physical Journal C: Particles and Fields
Online Access:https://doi.org/10.1140/epjc/s10052-025-14088-y
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author Xuhao Wu
Peng-Cheng Chu
Min Ju
He Liu
author_facet Xuhao Wu
Peng-Cheng Chu
Min Ju
He Liu
author_sort Xuhao Wu
collection DOAJ
description Abstract We investigate the properties of hybrid star and the mixed phase core to explore the radius ratio of the mixed phase in hybrid star. In the context of observed massive neutron stars (NSs), we examine the internal structure, phase transitions, and the impacts of the equation of state (EOS) in maximum hybrid star. We investigate the stiffness changes in the EOS during the hadron-quark phase transition within the hybrid stars. The relativistic mean-field (RMF) model is used to describe hadronic matter, while to the represent quark matter, the Nambu–Jona–Lasinio (NJL) model is applied. We explore the strength of vector coupling in quark matter, which delays the onset density of the mixed phase and reduces the size of the mixed-phase core in a hybrid star, but does not exhibit a clear correlation with the central density. In a hybrid star with a maximum mass of approximately 2 solar masses ( $$M_\odot $$ M ⊙ ), a mixed-phase core of $$\sim $$ ∼ 5 km may exist, comprising about $$40\%$$ 40 % of the total radius. However, our results do not support the existence of a sizable quark core containing the mixed phase ( $$R_\mathrm{{MP}}>1/2~R_\mathrm{{total}}$$ R MP > 1 / 2 R total ) for the maximum-mass hybrid star or for a 2  $$M_\odot $$ M ⊙ massive star.
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language English
publishDate 2025-03-01
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series European Physical Journal C: Particles and Fields
spelling doaj-art-d894316aa76e4aedbcb7f5bbc5da2b2f2025-08-20T02:49:35ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-03-0185311110.1140/epjc/s10052-025-14088-yThe mixed phase quark core in massive hybrid starsXuhao Wu0Peng-Cheng Chu1Min Ju2He Liu3Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan UniversityScience School, Qingdao University of TechnologySchool of Science, China University of Petroleum (East China)Science School, Qingdao University of TechnologyAbstract We investigate the properties of hybrid star and the mixed phase core to explore the radius ratio of the mixed phase in hybrid star. In the context of observed massive neutron stars (NSs), we examine the internal structure, phase transitions, and the impacts of the equation of state (EOS) in maximum hybrid star. We investigate the stiffness changes in the EOS during the hadron-quark phase transition within the hybrid stars. The relativistic mean-field (RMF) model is used to describe hadronic matter, while to the represent quark matter, the Nambu–Jona–Lasinio (NJL) model is applied. We explore the strength of vector coupling in quark matter, which delays the onset density of the mixed phase and reduces the size of the mixed-phase core in a hybrid star, but does not exhibit a clear correlation with the central density. In a hybrid star with a maximum mass of approximately 2 solar masses ( $$M_\odot $$ M ⊙ ), a mixed-phase core of $$\sim $$ ∼ 5 km may exist, comprising about $$40\%$$ 40 % of the total radius. However, our results do not support the existence of a sizable quark core containing the mixed phase ( $$R_\mathrm{{MP}}>1/2~R_\mathrm{{total}}$$ R MP > 1 / 2 R total ) for the maximum-mass hybrid star or for a 2  $$M_\odot $$ M ⊙ massive star.https://doi.org/10.1140/epjc/s10052-025-14088-y
spellingShingle Xuhao Wu
Peng-Cheng Chu
Min Ju
He Liu
The mixed phase quark core in massive hybrid stars
European Physical Journal C: Particles and Fields
title The mixed phase quark core in massive hybrid stars
title_full The mixed phase quark core in massive hybrid stars
title_fullStr The mixed phase quark core in massive hybrid stars
title_full_unstemmed The mixed phase quark core in massive hybrid stars
title_short The mixed phase quark core in massive hybrid stars
title_sort mixed phase quark core in massive hybrid stars
url https://doi.org/10.1140/epjc/s10052-025-14088-y
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