QCD equation of state and the structure of up-down quark stars in NJL model

The phase transition from a neutron star to a quark star and its relation to gamma-ray bursts are investigated. A new model: the 2 + 1 flavor Nambu–Jona-Lasinio (NJL) model with the method of proper-time regularization (PTR) is utilized for the quark phase; while the Relativistic Mean Field (RMF) theory is used for the hadronic phase. The process of phase transition is studied by considering the chemical potential, paying special attention to the phase transition point and the emergence of strange quark matter. Characteristics of compact stars are illustrated, and the energy release during the phase transition is found to be [Formula: see text] erg.

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Hybrid stars from a three-flavor NJL model with two kinds of tensor condensates

International Journal of Modern Physics E ◽

10.1142/s0218301320500937 ◽

2020 ◽

Vol 29 (10) ◽

pp. 2050093

Author(s):

Masatoshi Morimoto ◽

Yasuhiko Tsue ◽

João da Providência ◽

Constança Providência ◽

Masatoshi Yamamura

Keyword(s):

Equation Of State ◽

Quark Matter ◽

Thermodynamic Potential ◽

Chemical Potential ◽

Point Interaction ◽

Condensed Phases ◽

Charge Neutrality ◽

Njl Model ◽

Hybrid Stars ◽

The Relationship

To obtain the equation of state of quark matter and construct hybrid stars, we calculate the thermodynamic potential in the three-flavor Nambu–Jona-Lasinio model including the tensor-type four-point interaction and the Kobayashi–Maskawa–’t Hooft interaction. To construct the hybrid stars, it is necessary to impose the [Formula: see text] equilibrium and charge neutrality conditions on the system. It is shown that tensor condensed phases appear at large chemical potential. Under the possibility of the existence of the tensor condensates, the relationship between the radius and mass of hybrid stars is estimated.

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Stable Up-Down Quark Matter Nuggets, Quark Star Crusts, and a New Family of White Dwarfs

Galaxies ◽

10.3390/galaxies9040070 ◽

2021 ◽

Vol 9 (4) ◽

pp. 70

Author(s):

Lang Wang ◽

Jian Hu ◽

Cheng-Jun Xia ◽

Jian-Feng Xu ◽

Guang-Xiong Peng ◽

...

Keyword(s):

Quark Matter ◽

White Dwarfs ◽

Maximum Mass ◽

Quark Star ◽

Small Surface ◽

New Family ◽

Quark Stars ◽

Down Quark ◽

The Stability ◽

Chandrasekhar Limit

The possible existence of stable up-down quark matter (udQM) was recently proposed, and it was shown that the properties of udQM stars are consistent with various pulsar observations. In this work we investigate the stability of udQM nuggets and found at certain size those objects are more stable than others if a large symmetry energy and a small surface tension were adopted. In such cases, a crust made of udQM nuggets exists in quark stars. A new family of white dwarfs comprised entirely of udQM nuggets and electrons were also obtained, where the maximum mass approaches to the Chandrasekhar limit.

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On the stability of two-flavor and three-flavor quark matter in quark stars within the framework of NJL model

Modern Physics Letters A ◽

10.1142/s0217732320503216 ◽

2020 ◽

Vol 35 (39) ◽

pp. 2050321 ◽

Cited By ~ 1

Author(s):

Qianyi Wang ◽

Tong Zhao ◽

Hongshi Zong

Keyword(s):

Quark Matter ◽

Mean Field ◽

Field Approximation ◽

Mean Field Approximation ◽

Chiral Phase ◽

Quark Stars ◽

Njl Model ◽

The Stability ◽

Chiral Susceptibility ◽

Strong Interaction Matter

Following our recently proposed self-consistent mean field approximation approach, we have done some researches on the chiral phase transition of strong interaction matter within the framework of Nambu-Jona-Lasinio (NJL) model. The chiral susceptibility and equation of state (EOS) are computed in this work for both two-flavor and three-flavor quark matter for contrast. The Pauli–Villars scheme, which can preserve gauge invariance, is used in this paper. Moreover, whether the three-flavor quark matter is more stable than the two-flavor quark matter or not in quark stars is discussed in this work. In our model, when the bag constant are the same, the two-flavor quark matter has a higher pressure than the three-flavor quark matter, which is different from what Witten proposed in his pioneering work.

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