The QCD Equation of State and Quark Star Properties

Peshier, A.; Kämpfer, B.; Soff, G.

doi:10.1007/1-4020-3430-x_08

Cited by 3 publications

(3 citation statements)

References 25 publications

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“…In this section, we introduce the result from this approach: Equation (30). We introduce the light and strange chiral condensates, thermodynamic quantities, quark number density and susceptibility, and finally the chiral phase transition.…”

Section: Resultsmentioning

confidence: 99%

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Thermodynamics and higher order moments in SU(3) linear σ-model with gluonic quasiparticles

Tawfik

Magdy

2014

J. Phys. G: Nucl. Part. Phys.

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In framework of linear σ-model (LSM) with three quark flavors, the chiral phase-diagram at finite temperature and density is investigated. At temperatures higher than the critical temperature (T c ), we added to LSM the gluonic sector from the quasi-particle model (QPM), which assumes that the interacting gluons in the strongly interacting matter, the quark-gluon plasma (QGP), are phenomenologically the same as non-interacting massive quasi-particles. The dependence of the chiral condensates of strange and non-strange quarks on temperature and chemical potential is analysed.Then, we have calculated the thermodynamics in the new approach (combination of LSM and QPM).Confronting the results with recent lattice QCD simulations shows an excellent agreement in almost all thermodynamic quantities. The first and second order moments of particle multiplicity are studied in dependence on the chemical potential but at fixed temperature and on the chemical potential but at fixed temperature. These are implemented in characterizing the large fluctuations accompanying the chiral phase-transition. The results of first and second order moments are compared with the SU(3) Polyakov linear σ-model (PLSM). Also, the resulting phase-diagrams deduced in PLSM and LSM+QPM are compared with each other. The interactions between the basic building blocks (quarks, gluons, leptons and force mediators) of the visible matter in the Universe are controlled by fundamental interactions (except gravity). The quantum electrodynamics (QED) gives a very good description for the electromagnetic phenomena. The strong interaction can be described by the quantum chromodynamics (QCD) with an asymptotic freedom [1, 2] meaning that the strong coupling becomes small when the momentum scale for the considered processes becomes large. This leads to a phase transition from hadronic matter, in which quarks and gluons are confined at low temperature and density to a new state-of-mater [3, 4], called quark-gluon plasma (QGP), in which quarks and gluons are no longer confined at high temperature and large density [5]. The theoretical and experimental studies of QGP still represent a challenge to be faced by scientists. So far, there are many heavy-ion experiments aiming to create that phase of matter and to study its properties for example the ones operating with the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC). From theoretical point-of-view, there are -apart from QCD and its numerical simulations -many first-principle models, like perturbative Nambu-Jona-Lasinio (PNJL) model [6-8], Polyakov linear σ-model (PLSM), Polyakov quark meson model (PQM) [9][10][11]. Also the quasi-particle model (QPM) [12][13][14] was suggested to reproduce the lattice QCD calculations. Each of these model has strong and weak features. The compilation between different effective models was suggested [15], for instance, an extension in NJL to include Hadron Resonance Gas (HRG). In the present paper, we implement the same compilation aiming to fully reproduce...

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Section: Resultsmentioning

confidence: 99%

“…, which can be adjusted to reproduce the lattice QCD calculations [30] and reflect the non-perturbative effects.…”

Section: The Su(3) Approachesmentioning

confidence: 99%

Thermodynamics and higher order moments in SU(3) linear σ-model with gluonic quasiparticles

Tawfik

Magdy

2014

J. Phys. G: Nucl. Part. Phys.

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“…An evaluation of ( 29) for the present model for the QCD pressure would require its extension to a finite µ q , which we will perform in a subsequent work. In the present model, we used our knowledge of the composition as a function of temperature to define a proxy for (29) by interpolating between the two known limits (30) and (31) with the partial pressure of the HRG, x HRG (T) = P MHRG (T)/P tot (T), as…”

Section: Quark Number Susceptibilitiesmentioning

confidence: 99%

Quark Cluster Expansion Model for Interpreting Finite-T Lattice QCD Thermodynamics

2021

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In this work, we present a unified approach to the thermodynamics of hadron–quark–gluon matter at finite temperatures on the basis of a quark cluster expansion in the form of a generalized Beth–Uhlenbeck approach with a generic ansatz for the hadronic phase shifts that fulfills the Levinson theorem. The change in the composition of the system from a hadron resonance gas to a quark–gluon plasma takes place in the narrow temperature interval of 150–190 MeV, where the Mott dissociation of hadrons is triggered by the dropping quark mass as a result of the restoration of chiral symmetry. The deconfinement of quark and gluon degrees of freedom is regulated by the Polyakov loop variable that signals the breaking of the Z(3) center symmetry of the color SU(3) group of QCD. We suggest a Polyakov-loop quark–gluon plasma model with O(αs) virial correction and solve the stationarity condition of the thermodynamic potential (gap equation) for the Polyakov loop. The resulting pressure is in excellent agreement with lattice QCD simulations up to high temperatures.

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Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach

Blaschke,

Cierniak,

Ivanytskyi

et al. 2024

Eur. Phys. J. A

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We describe multiquark clusters in quark matter within a Beth-Uhlenbeck approach in a background gluon field coupled to the underlying chiral quark dynamics using the Polyakov gauge. An effective potential for the traced Polyakov loop is used to establish the center symmetry of the SU(3) color which suppresses colored states and its dynamical breaking as an aspect of the confinement/deconfinement transition. Quark confinement is modeled by a large quark mass in vacuum which is motivated by a confining density functional approach. A multiquark cluster containing n quarks and antiquarks is described as a binary composite of smaller subclusters $$n_1$$ n 1 and $$n_2$$ n 2 ($$n_1+n_2=n$$ n 1 + n 2 = n ). It has a spectrum consisting of a bound state and a scattering state continuum. For the corresponding cluster-cluster phase shifts we use simple ansätze that capture the Mott dissociation of clusters as a function of temperature and chemical potential. We go beyond the simple “step-up-step-down” model that ignores continuum correlations and introduce an improved model that includes them in a generic form. In order to explain the model, we restrict ourselves here to the cases where the cluster size is $$1 \le n \le 6$$ 1 ≤ n ≤ 6 . A striking result is the suppression of the abundance of colored multiquark clusters at low temperatures by the coupling to the Polyakov loop and their importance for a quantitative description of lattice QCD thermodynamics at non-vanishing baryochemical potentials. An important ingredient are Polyakov-loop generalized distribution functions of n-quark clusters which are derived here for the first time. Within our approach we calculate thermodynamic properties such as baryon density and entropy. We demonstrate that the limits of a hadron resonance gas at low temperatures and $$\mathcal {O}(g^2)$$ O ( g 2 ) perturbative QCD at high temperatures are correctly reproduced. A comparison with lattice calculations shows that our model is able to give a unified, systematic approach to describe properties of the quark-gluon-hadron system.

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The QCD Equation of State and Quark Star Properties

Abstract: We review our quasiparticle model for the thermodynamics of strongly interacting matter at high temperature, and its extrapolation to non-zero chemical potential. Some implications of the resulting soft equation of state of quark matter at low temperatures are pointed out.

Cited by 3 publications

References 25 publications

Thermodynamics and higher order moments in SU(3) linear σ-model with gluonic quasiparticles

Thermodynamics and higher order moments in SU(3) linear σ-model with gluonic quasiparticles

Quark Cluster Expansion Model for Interpreting Finite-T Lattice QCD Thermodynamics

Thermodynamics of quark matter with multiquark clusters in an effective Beth-Uhlenbeck type approach

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