Nonstrange and strange quark matter at finite temperature within modified NJL model and protoquark stars

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Main Authors: Yuan, Wen-Li, Yasutake, Nobutoshi, Xu, Renxin
Format: Preprint
Published: 2025
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author Yuan, Wen-Li
Yasutake, Nobutoshi
Xu, Renxin
author_facet Yuan, Wen-Li
Yasutake, Nobutoshi
Xu, Renxin
contents We extend the modified Nambu-Jona-Lasinio (NJL) model -- incorporating exchange interactions via the Fierz transformation -- to finite temperatures in both two- and three-flavor scenarios, and investigate the properties of protoquark stars in $β$-equilibrium. Our results show that increasing the strength of exchange interactions, characterized by the parameter $α$, changes the chiral phase transition from first-order to crossover. We examine the effects of finite temperature, lepton fraction, and exchange interactions on the equation of state (EOS). We find that, in the crossover regime, the EOS is significantly stiffer than in the first-order case due to the substantial contribution of repulsive interactions in the exchange channels, while it remains relatively insensitive to variations in temperature and lepton fraction. Imposing the thermodynamic consistency, which requires the minimum of free energy per baryon $f / ρ_B$ occurs at zero pressure, further constrains the minimum value of vacuum pressure.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14795
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Nonstrange and strange quark matter at finite temperature within modified NJL model and protoquark stars
Yuan, Wen-Li
Yasutake, Nobutoshi
Xu, Renxin
High Energy Physics - Phenomenology
High Energy Astrophysical Phenomena
We extend the modified Nambu-Jona-Lasinio (NJL) model -- incorporating exchange interactions via the Fierz transformation -- to finite temperatures in both two- and three-flavor scenarios, and investigate the properties of protoquark stars in $β$-equilibrium. Our results show that increasing the strength of exchange interactions, characterized by the parameter $α$, changes the chiral phase transition from first-order to crossover. We examine the effects of finite temperature, lepton fraction, and exchange interactions on the equation of state (EOS). We find that, in the crossover regime, the EOS is significantly stiffer than in the first-order case due to the substantial contribution of repulsive interactions in the exchange channels, while it remains relatively insensitive to variations in temperature and lepton fraction. Imposing the thermodynamic consistency, which requires the minimum of free energy per baryon $f / ρ_B$ occurs at zero pressure, further constrains the minimum value of vacuum pressure.
title Nonstrange and strange quark matter at finite temperature within modified NJL model and protoquark stars
topic High Energy Physics - Phenomenology
High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2508.14795