scholarly journals Hadron–Quark Phase Transition in the SU (3) Local Nambu–Jona-Lasinio (NJL) Model with Vector Interaction

Symmetry ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 124 ◽  
Author(s):  
Grigor Alaverdyan
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Chemical Potential ◽  
Hadronic Matter ◽  
Coupling Constant ◽  
Vector Coupling ◽  
Vector Coupling Constant ◽  
Njl Model ◽  
Matter Phase ◽  
Quark Phase

We study the hadron–quark hybrid equation of state (EOS) of compact-star matter. The Nambu–Jona-Lasinio (NJL) local SU (3) model with vector-type interaction is used to describe the quark matter phase, while the relativistic mean field (RMF) theory with the scalar-isovector δ-meson effective field is adopted to describe the hadronic matter phase. It is shown that the larger the vector coupling constant GV, the lower the threshold density for the appearance of strange quarks. For a sufficiently small value of the vector coupling constant, the functions of the mass dependence on the baryonic chemical potential have regions of ambiguity that lead to a phase transition in nonstrange quark matter with an abrupt change in the baryon number density. We show that within the framework of the NJL model, the hypothesis on the absolute stability of strange quark matter is not realized. In order to describe the phase transition from hadronic matter to quark matter, Maxwell’s construction is applied. It is shown that the greater the vector coupling, the greater the stiffness of the EOS for quark matter and the phase transition pressure. Our results indicate that the infinitesimal core of the quark phase, formed in the center of the neutron star, is stable.

scholarly journals Hadron-Quark Phase Transition in the SU(3) Local Nambu – Jona-Lasinio (NJL) Model with Vector Interaction

2020 ◽  
Author(s):  
Grigor Alaverdyan
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Strange Quark ◽  
Hadronic Matter ◽  
Coupling Constant ◽  
Vector Coupling ◽  
Vector Coupling Constant ◽  
Njl Model ◽  
Matter Phase ◽  
Quark Phase

We study the hadron-quark hybrid equation of state (EOS) of compact-star matter. The Nambu—Jona-Lasinio (NJL) local SU(3) model with vector-type interaction is used to describe the quark matter phase, while the relativistic mean field (RMF) theory with scalar-isovector $\delta$-meson effective field adopted to describe the hadronic matter phase. It is shown that the larger the vector coupling constant, the lower the threshold density for the appearance of strange quarks. For a sufficiently small value of the vector coupling constant, the functions of the mass dependence on the baryonic chemical potential have regions of ambiguity which leads to a phase transition in non-strange quark matter with an abrupt change in the baryon number density. We show that within the framework of the NJL model, the hypothesis on the absolute stability of strange quark matter is not realized. In order to describe the phase transition from hadronic matter to quark matter, the Maxwell's construction is applied. It is shown that the greater the vector coupling, the greater the stiffness of the EOS for quark matter and the phase transition pressure. Our results indicate that the infinitesimal core of the quark phase, formed in the center of the neutron star, is stable.

scholarly journals INVESTIGATION OF THE EXISTENCE OF HYBRID STARS USING NAMBU–JONA–LASINIO MODELS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1521-1524 ◽  
Author(s):  
J. G. COELHO ◽  
C. H. LENZI ◽  
M. MALHEIRO ◽  
R. M. MARINHO ◽  
M. FIOLHAIS
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quark Matter ◽  
Chemical Potential ◽  
Compact Stars ◽  
Vector Coupling ◽  
Njl Model ◽  
Hybrid Stars ◽  
Quark Phase

We investigate the hadron-quark phase transition inside neutron stars and obtain mass–radius relations for hybrid stars. The equation of state for the quark phase using the standard NJL model is too soft, leading to an unstable star and suggesting a modification of the NJL model by introducing a momentum cutoff dependent on the chemical potential. However, even in this approach, the instability remains. In order to remedy the instability we suggest the introduction of a vector coupling in the NJL model, which makes the EoS stiffer, reducing the instability. We conclude that the possible existence of quark matter inside the stars require high densities, leading to very compact stars.

HYBRID STARS WITH DELTA MATTER AND COLOR–FLAVOR LOCKED QUARK PHASE

2008 ◽  
Vol 17 (05) ◽  
pp. 737-746 ◽  
Author(s):  
H. RODRIGUES ◽  
J. C. T. OLIVEIRA ◽  
S. B. DUARTE
Keyword(s):  
Phase Transition ◽  
Quark Matter ◽  
Strange Quark ◽  
Bose Condensate ◽  
Hadronic Matter ◽  
Hybrid Stars ◽  
S Quarks ◽  
Quark Phase ◽  
Color Superconductor

The color–flavor locked (CFL) phase is believed to be the fundamental state of strange quark matter (SQM) at high densities. The CFL phase is a color superconductor composed of pairs of u, d and s quarks, with no electrons, forming a Bose condensate. In this work, we analyze a possible phase transition of hadronic matter made of nucleons, Δ–resonances, hyperons and leptons, to CFL superconducting quark matter. An equation of state taking into account this phase transition is employed to determine the characteristics of a hybrid star. The role of the color superconducting gap on the hybrid stars properties is also discussed.

scholarly journals Impact of quark deconfinement in neutron star mergers and hybrid star mergers

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3595-3604
Author(s):  
Andreas Bauswein ◽  
Sebastian Blacker
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Hadronic Matter ◽  
Hybrid Star ◽  
Strong Phase ◽  
Quark Deconfinement ◽  
Wave Signature ◽  
Quark Phase

AbstractWe describe an unambiguous gravitational-wave signature to identify the occurrence of a strong phase transition from hadronic matter to deconfined quark matter in neutron star mergers. Such a phase transition leads to a strong softening of the equation of state and hence to more compact merger remnants compared to purely hadronic models. If a phase transition takes place during merging, this results in a characteristic increase of the dominant postmerger gravitational-wave frequency relative to the tidal deformability characterizing the inspiral phase. By comparing results from different purely hadronic and hybrid models we show that a strong phase transition can be identified from a single, simultaneous measurement of pre- and postmerger gravitational waves. Furthermore, we present new results for hybrid star mergers, which contain quark matter already during the inspiral stage. Also for these systems we find that the postmerger GW frequency is increased compared to purely hadronic models. We thus conclude that also hybrid star mergers with an onset of the hadron-quark phase transition at relatively low densities may lead to the very same characteristic signature of quark deconfinement in the postmerger GW signal as systems undergoing the phase transition during merging.

Studies on proper time regularization and the QCD chiral phase transition

2019 ◽  
Vol 34 (01) ◽  
pp. 1950003
Author(s):  
Yu-Qiang Cui ◽  
Zhong-Liang Pan
Keyword(s):  
Phase Transition ◽  
Small Parameter ◽  
Effective Mass ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Proper Time ◽  
Chiral Phase ◽  
Chiral Phase Transition ◽  
Njl Model ◽  
The Difference

We investigate the finite-temperature and zero quark chemical potential QCD chiral phase transition of strongly interacting matter within the two-flavor Nambu–Jona-Lasinio (NJL) model as well as the proper time regularization. We use two different regularization processes, as discussed in Refs. 36 and 37, separately, to discuss how the effective mass M varies with the temperature T. Based on the calculation, we find that the M of both regularization schemes decreases when T increases. However, for three different parameter sets, quite different behaviors will show up. The results obtained by the method in Ref. 36 are very close to each other, but those in Ref. 37 are getting farther and farther from each other. This means that although the method in Ref. 37 seems physically more reasonable, it loses the advantage in Ref. 36 of a small parameter dependence. In addition, we also, find that two regularization schemes provide similar results when T [Formula: see text] 100 MeV, while when T is larger than 100 MeV, the difference becomes obvious: the M calculated by the method in Ref. 36 decreases more rapidly than that in Ref. 37.

Universality of the Weak Vector Coupling Constant

1970 ◽  
Vol 1 (5) ◽  
pp. 1360-1373 ◽  
Author(s):  
Duane A. Dicus ◽  
Richard E. Norton
Keyword(s):  
Coupling Constant ◽  
Vector Coupling ◽  
Vector Coupling Constant ◽  
Weak Vector

scholarly journals The QCD Phase-Diagram Obtained from the NJL and the Extended-NJL Models for Quark and Hadron Phases

2017 ◽  
Vol 45 ◽  
pp. 1760059
Author(s):  
Clebson A. Graeff ◽  
Débora P. Menezes
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Equations Of State ◽  
Original Formulation ◽  
Qcd Phase Diagram ◽  
Hadron Phase ◽  
Vector Interaction ◽  
Njl Model ◽  
Quark Phase

We analyse the hadron/quark phase transition described by the Nambu-Jona-Lasinio (NJL) model [quark phase] and the extended Nambu-Jona-Lasinio model (eNJL) [hadron phase]. While the original formulation of the NJL model is not capable of describing hadronic properties due to its lack of confinement, it can be extended with a scalar-vector interaction so it exhibits this property, the so-called eNJL model. As part of this analysis, we obtain the equations of state within the SU(2) versions of both models for the hadron and the quark phases and determine the binodal surface.

On the renormalization of the axial vector coupling constant in β-decay

1960 ◽  
Vol 16 (3) ◽  
pp. 560-568 ◽  
Author(s):  
J. Bernstein ◽  
M. Gell-Mann ◽  
L. Michel
Keyword(s):  
Axial Vector ◽  
Coupling Constant ◽  
Β Decay ◽  
Vector Coupling ◽  
Vector Coupling Constant ◽  
Axial Vector Coupling
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