https://doi.org/10.1140/epjc/s10052-025-14088-y
Regular Article - Theoretical Physics
The mixed phase quark core in massive hybrid stars
1
Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, 066004, Qinhuangdao, China
2
Science School, Qingdao University of Technology, 266000, Qingdao, China
3
The Research Center of Theoretical Physics, Qingdao University of Technology, 266033, Qingdao, China
4
School of Science, China University of Petroleum (East China), 266580, Qingdao, China
Received:
23
October
2024
Accepted:
16
March
2025
Published online:
29
March
2025
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 (
), a mixed-phase core of 
5 km may exist, comprising about 
of the total radius. However, our results do not support the existence of a sizable quark core containing the mixed phase (
) for the maximum-mass hybrid star or for a 2 massive star.
© The Author(s) 2025
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Funded by SCOAP3.
