scholarly journals Nonperturbative quark matter equations of state with vector interactions

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3629-3649
Author(s):  
Konstantin Otto ◽  
Micaela Oertel ◽  
Bernd-Jochen Schaefer
Keyword(s):  
Vector Meson ◽  
Quark Matter ◽  
Chemical Potential ◽  
Equations Of State ◽  
Vector Mesons ◽  
Solar Mass ◽  
Scalar Mesons ◽  
Grand Potential ◽  
Hybrid Stars ◽  
Pseudo Scalar

AbstractNonperturbative equations of state (EoSs) for two and three quark flavors are constructed with the functional renormalization group (FRG) within a quark-meson model truncation augmented by vector mesons for low temperature and high density. Based on previous FRG studies without repulsive vector meson interactions the influence of isoscalar vector ω- and ϕ-mesons on the dynamical fluctuations of quarks and (pseudo)scalar mesons is investigated. The grand potential as well as vector meson condensates are evaluated as a function of quark chemical potential and the quark matter EoS in β-equilibrium is applied to neutron star (NS) physics. The tidal deformability and mass-radius relations for hybrid stars from combined hadronic and quark matter EoSs are compared for different vector couplings. We observe a significant impact of the vector mesons on the quark matter EoS such that the resulting EoS is sufficiently stiff to support two-solar-mass neutron stars.

Quark matter in the perturbation QCD model with a rapidly convergent matching-invariant running coupling

2017 ◽  
Vol 26 (06) ◽  
pp. 1750034 ◽  
Author(s):  
Jian-Feng Xu ◽  
Yan-An Luo ◽  
Lei Li ◽  
Guang-Xiong Peng
Keyword(s):  
Perturbation Theory ◽  
Infinite Number ◽  
Quark Matter ◽  
Chemical Potential ◽  
Maximum Mass ◽  
Solar Mass ◽  
Quark Stars ◽  
Dense Quark Matter ◽  
Subtraction Point ◽  
Running Coupling

The properties of dense quark matter are investigated in the perturbation theory with a rapidly convergent matching-invariant running coupling. The fast convergence is mainly due to the resummation of an infinite number of known logarithmic terms in a compact form. The only parameter in this model, the ratio of the renormalization subtraction point to the chemical potential, is restricted to be about 2.64 according to the Witten–Bodmer conjecture, which gives the maximum mass and the biggest radius of quark stars to be, respectively, two times the solar mass and 11.7[Formula: see text]km.

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

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.

scholarly journals Two Novel Approaches to the Hadron-Quark Mixed Phase in Compact Stars

Universe ◽  
2018 ◽  
Vol 4 (9) ◽  
pp. 94 ◽  
Author(s):  
Vahagn Abgaryan ◽  
David Alvarez-Castillo ◽  
Alexander Ayriyan ◽  
David Blaschke ◽  
Hovik Grigorian
Keyword(s):  
Quark Matter ◽  
Chemical Potential ◽  
Equations Of State ◽  
Polynomial Interpolation ◽  
Compact Star ◽  
Compact Stars ◽  
Weight Functions ◽  
Geometrical Structures ◽  
First Order ◽  
Maxwell Construction

First-order phase transitions, such as the liquid-gas transition, proceed via formation of structures, such as bubbles and droplets. In strongly interacting compact star matter, at the crust-core transition but also the hadron-quark transition in the core, these structures form different shapes dubbed “pasta phases”. We describe two methods to obtain one-parameter families of hybrid equations of state (EoS) substituting the Maxwell construction that mimic the thermodynamic behaviour of pasta phase in between a low-density hadron and a high-density quark matter phase without explicitly computing geometrical structures. Both methods reproduce the Maxwell construction as a limiting case. The first method replaces the behaviour of pressure against chemical potential in a finite region around the critical pressure of the Maxwell construction by a polynomial interpolation. The second method uses extrapolations of the hadronic and quark matter EoS beyond the Maxwell point to define a mixing of both with weight functions bounded by finite limits around the Maxwell point. We apply both methods to the case of a hybrid EoS with a strong first order transition that entails the formation of a third family of compact stars and the corresponding mass twin phenomenon. For both models, we investigate the robustness of this phenomenon against variation of the single parameter: the pressure increment at the critical chemical potential that quantifies the deviation from the Maxwell construction. We also show sets of results for compact star observables other than mass and radius, namely the moment of inertia and the baryon mass.

scholarly journals Bayesian Analysis for Extracting Properties of the Nuclear Equation of State from Observational Data Including Tidal Deformability from GW170817

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 61 ◽  
Author(s):  
Alexander Ayriyan ◽  
David Alvarez-Castillo ◽  
David Blaschke ◽  
Hovik Grigorian
Keyword(s):  
Equation Of State ◽  
Bayesian Analysis ◽  
Quark Matter ◽  
Equations Of State ◽  
Compact Star ◽  
String Tension ◽  
Model Parameters ◽  
Analysis Method ◽  
Hybrid Stars ◽  
Limiting Case

We develop a Bayesian analysis method for selecting the most probable equation of state under a set of constraints from compact star physics, which now include the tidal deformability from GW170817. We apply this method for the first time to a two-parameter family of hybrid equations of state that is based on realistic models for the hadronic phase (KVORcut02) and the quark matter phase (SFM α ) which produce a third family of hybrid stars in the mass–radius diagram. One parameter ( α ) characterizes the screening of the string tension in the string-flip model of quark matter while the other ( Δ P ) belongs to the mixed phase construction that mimics the thermodynamics of pasta phases and includes the Maxwell construction as a limiting case for Δ P = 0 . We present the corresponding results for compact star properties like mass, radius and tidal deformabilities and use empirical data for them in the newly developed Bayesian analysis method to obtain the probabilities for the model parameters within their considered range.

A phenomenological study of hybrid stars in which the crossover transition from quark to hadron makes the EOS stiffer in contrast to the hybrid EOS based on Maxwell condition

2017 ◽  
Vol 32 (08) ◽  
pp. 1750051 ◽  
Author(s):  
Tong Zhao ◽  
Cheng-Ming Li ◽  
Ya-Peng Zhao ◽  
Yan Yan ◽  
Xin-Lian Luo ◽  
...  
Keyword(s):  
Phenomenological Study ◽  
Equations Of State ◽  
Point Of View ◽  
Hadronic Matter ◽  
Solar Mass ◽  
Hadron Phase ◽  
Crossover Phase ◽  
The Rich ◽  
Hybrid Stars ◽  
Relationship Of

In this paper, we make a phenomenological study of the mass–radii relationship of hybrid stars from the point of view of the smooth crossover phase transition. We find a way to construct stiff hybrid equations of state (EOSs) with soft EOSs of both the quark matter and the hadronic matter. For the hadron phase, we adopt the EOS softened by introducing hyperons that are considered to exist in the core of a neutron star. For the quark phase, we introduce a quark EOS based on the Dyson–Schwinger equation (DSE) that is calculated in our previous work, and it is also a soft EOS. In contrast to the hybrid EOS based on Maxwell condition, we find that the resulting EOS is stiff and the maximum mass of the hybrid stars is still about two times of solar mass. This result indicates the rich possibilities of the crossover model.

scholarly journals Masses and decay constants of (axial-)vector mesons at finite chemical potential

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
Pascal J. Gunkel ◽  
Christian S. Fischer
Keyword(s):  
Bound States ◽  
Chemical Potential ◽  
Axial Vector ◽  
Landau Gauge ◽  
Vector Mesons ◽  
Coexistence Region ◽  
Decay Constants ◽  
First Order ◽  
Chemical Potentials ◽  
Pseudo Scalar

AbstractWe update our previous results for (pseudo-)scalar mesons at zero temperature and finite quark chemical potential and generalize the investigation to include (axial-)vector mesons. We determine bound-state properties such as meson masses and decay constants up to chemical potentials far in the first-order coexistence region. To extract the bound-states properties, we solve the Bethe-Salpeter equation and utilize Landau-gauge quark and gluon propagators obtained from a coupled set of (truncated) Dyson-Schwinger equations with $$N_{\text{ f }}=2+1$$ N f = 2 + 1 dynamical quark flavors at finite chemical potential and vanishing temperature. For multiple (pseudo-)scalar and (axial-)vector mesons, we observe constant masses and decay constants for chemical potentials up to the coexistence region of the first-order phase transition thus verifying explicitly the Silver-Blaze property of QCD. Inside the coexistence region the pion becomes more massive and its decay constants decrease, whereas corresponding quantities for the (axial-)vector mesons remain (almost) constant.

scholarly journals MESONIC CORRELATION FUNCTIONS AT FINITE TEMPERATURE AND DENSITY IN THE NAMBU–JONA–LASINIO MODEL WITH A POLYAKOV LOOP

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2249-2255
Author(s):  
HUBERT HANSEN
Keyword(s):  
Chiral Symmetry ◽  
Finite Temperature ◽  
Chemical Potential ◽  
Chiral Symmetry Breaking ◽  
Goldstone Boson ◽  
Polyakov Loop ◽  
Scalar Mesons ◽  
Njl Model ◽  
Pnjl Model ◽  
Pseudo Scalar

We investigate the properties of scalar and pseudo-scalar mesons at finite temperature and quark chemical potential in the framework of the Nambu–Jona-Lasinio (NJL) model coupled to the Polyakov loop (PNJL model) with the aim of taking into account features of both chiral symmetry breaking and deconfinement. In the phase of broken chiral symmetry a narrower width for the σ meson is obtained with respect to the NJL case; on the other hand, the pion still behaves as a Goldstone boson.

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.

scholarly journals Quarks and light (pseudo-)scalar mesons at finite chemical potential

2019 ◽  
Vol 55 (9) ◽  
Author(s):  
Pascal J. Gunkel ◽  
Christian S. Fischer ◽  
Philipp Isserstedt
Keyword(s):  
Chemical Potential ◽  
Scalar Mesons ◽  
Pseudo Scalar
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