Magnetized strange quark matter in a mass-density-dependent model

We investigate the properties of strange quark matter (SQM) in a strong magnetic field with quark confinement by the density dependence of quark masses considering the total baryon number conservation, charge neutrality and chemical equilibrium. It is found that an additional term should appear in the pressure expression to maintain thermodynamic consistency. At fixed density, the energy density of magnetized SQM varies with the magnetic field strength. By increasing the field strength an energy minimum exists located at about 6×10¹⁹ Gauss when the density is fixed at two times the normal nuclear saturation density.     

A phenomenological quark matter equation of state

Both the MIT bag model and potential models are able to reproduce static properties of hadrons (e.g. their mass spectrum) with reasonable accuracy. However, while the extrapolation of the MIT bag model from hadrons to dense matter is rather straightforward, it is not the same for potential models. To deal with this problem, in this paper, the methods of relativistic quantum many-body theory are applied to the study of quark matter interacting through an instantaneous potential at zero temperature. It is shown that under some conditions, the quark plasma undergoes a first order transition from a massive state at low density to a gas of particles of decreasing mass at high density—as one expects from perturbative QCD. In addition, immediately after the transition, the quarks are in a collective bound state, which might perhaps be interpreted as the fact that they just start to leave the inside of hadrons.     

Gluon condensates,quark matter equation of state and quark stars

We consider here quark matter equation of state including strange quarks and taking into account a nontrivial vacuum structure for QCD with gluon condensates. The parameters of condendsate function are determined from minimisation of the thermodynamic potential. The scale parameter of the gluon condensates is fixed from the SVZ parameter in the context of QCD sum rules at zero temperature and zero baryon density. The equation of state for strange matter at zero temperature as derived is used to study quark star structure using Tolman Oppenheimer Volkoff equations. Stable solutions for quark stars are obtained with a large Chandrasekhar limit as 3.2M and radii around 17 kms.     

Strange quark matter with dynamically generated quark masses

Bulk properties of strange quark matter (SQM) are investigated within the SU(3) Nambu–Jona-Lasinio model. In the chiral limit the model behaves very similarly to the MIT bag model which is often used to describe SQM. However, when we introduce realistic current quark masses, the strange quark becomes strongly disfavored, because of its large dynamical mass. We conclude that SQM is not absolutely stable.     

Strange quark dynamics on hot dense matter under the extreme condition

Production and properties of φ-meson under the extreme hot dense matter which is formed in Au + Au collisions at RHIC energy have been briefly reviewed.The issues are focused on transverse momentum (p T ) spectra of φ,elliptic flow of φ,nuclear modification factor of φ,the ratio of Ω(p T )/φ(p T ) versus p T,the ratio of Ω(p T /3)/φ(p T /2) versus p T /n q,spin alignment of φ and the enhancement of φ etc.These observables give the significant information of the strange quark dynamics in hot dense matter under the extreme condition.     

Strange quark dynamics on hot dense matter under the extreme condition

Production and properties of φ-meson under the extreme hot dense matter which is formed in Au ＋ Au collisions at RHIC energy have been briefly reviewed.The issues are focused on transverse momentum （p T ） spectra of φ,elliptic flow of φ,nuclear modification factor of φ,the ratio of Ω（p T ）/φ（p T ） versus p T,the ratio of Ω（p T /3）/φ（p T /2） versus p T /n q,spin alignment of φ and the enhancement of φ etc.These observables give the significant information of the strange quark dynamics in hot dense matter under the extreme condition.     

Equation of state of zero-temperature quark matter

We outline the key elements of a recent calculation aimed at determining the equation of state of deconfined (but unpaired) quark matter at zero temperature and high density, using finite quark masses. The computation is performed in perturbation theory up to three loops, and necessitates the development and application of some novel computational tools. In this talk, we introduce the basic features of these new techniques and review the main sources of motivation for considering finite mass effects in perturbation theory.     

Relativistic shocks in the systems containing domains with anomalous equation of state and quark baryonic matter hadronization

Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition.     

Relativistic shocks in the systems containing domains with anomalous equation of state and quark baryonic matter hadronization

Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition.     

Strange quark content in the nucleon

Though none of the experimental evidences for the strange quark contributions to nucleon properties is explained convincingly by an alternative, the recent experiments, even HAPPEX Collab. and A4 Collab., on a measurement of the parity-violating asymmetries show no strangeness in the proton. Despite this conclusion we demonstrate here no accidental compatibility of our theoretical predictions for nucleon strange form factors with some nonzero parity violation experimental results which strengthens our belief in the strangeness in the nucleon.     

Strange quark star and the parameter space of the quasi-particle model

The properties of strange quark stars are studied within the quasi-particle model. Taking into account chemical equilibrium and charge neutrality, the equation of state(EOS) of(2+ 1)-flavor quark matter is obtained. We illustrate the parameter spaces with constraints from two aspects: one is based on the astronomical results of PSR J0740+ 6620 and GW 170 817,and the other is based on the constraints proposed from the theoretical study of a compact star that the EOS must ensure the tidal deformability Λ_(1.4)=190_(-120)~(+390) and support a maximum mass above 1.97M_⊙. It is found that neither type of constraints can restrict the parameter space of the quasi-particle model in a reliable region and thus we conclude that the low mass compact star cannot be a strange quark star.     

凝聚态物质状态方程的一个数值模型

建立了凝聚态物质的一个三项式状态方程：以Faussurier平均原子模型为基础计算电子热压和电子热能;以Cowan模型为基础计算离子热压和离子热能;用基于实验数据的半经验拟合公式计算物质的冷压和冷能。用实验数据检验了用平均原子模型计算的平均电离度。将状态方程与Hugoniot关系式相结合,计算了Be和Al的冲击绝热曲线,结果充分地展现出电子在高温、高密度条件下的壳层结构效应。     

Bulk viscosity of strange quark matter in density dependent quark mass model

We have studied the bulk viscosity of strange quark matter in the density dependent quark mass model (DDQM) and compared results with calculations done earlier in the MIT bag model where u, d masses were neglected and first order interactions were taken into account. We find that at low temperatures and high relative perturbations, the bulk viscosity is higher by 2 to 3 orders of magnitude while at low perturbations the enhancement is by 1–2 order of magnitude as compared to earlier results. Also the damping time is 2–3 orders of magnitude lower implying that the star reaches stability much earlier than in MIT bag model calculations.     

The di-hyperon state in the quark cluster model

The di-hyperon state (DH) predicted by Jaffe in the MIT bag model is studied in the non-relativistic quark cluster model. The resonating group method is applied to the ΛΛ, NΞ and ΣΣ coupled channels problem. No stable bound state is found below the lowest ΛΛ threshold but a sharp resonance with spin-parity 0⁺ is predicted just below the NΞ threshold. The structure of the state is similar to that of the flavour SU₃ singlet state and the attractive nature of the color magnetic interaction in this state is responsible for the appearance of the resonance. The difference between the present model and the bag model which predicted a strongly bound state is attributed to the difference in the mechanism of confinement for these two models.     

Ground state baryons in the non-relativistic quark model

We analyse the properties of the ground state bayons in the non-relativistic quark model. The three-body problem is solved by means of the hyperspherical expansion. We consider various two-body potentials of power law type and also a three-body linear potential. In displaying the results, we insist on quantities like ratios of splittings which are scale independent and are functions only of the power of the potential and of the ratio of quark masses.     

Strange quark mass (ms) dependent model of anisotropic strange quark star

This article presents the configuration of strange quark stars in hydrostatic equilibrium considering the Vaidya-Tikekar metric ansatz.The interior of such stars comprises strange quark matter(henceforth SQM),whose equation of state(henceforth EoS) is described by the MIT EoS p=1/3(ρ-4B),where B is the difference between perturbative and non-perturbative vacuum.We have included the mass of the strange quark(m_s) into the EoS and studied its effect on the overall properties of the stran...     

Wide-range equation of state of matter. II. Microfield model

Among the models proposed for theoretically calculating wide-range equations of state of matter we single out: the ionization — chemical equilibrium model for the gas — plasma state of matter containing a qualitatively new nonidealness correction, the microfield correction; the quantum — statistical model for compressed condensed matter; the quasiband model for the transition region between these states. It is shown that, taken together, these models are in good agreement with experiments, give the most accurate equation of state in the supercritical region to date, and provide a qualitative explanation of the optical properties of matter.The work was performed with the financial support of the Russian Fund for fundamental research (Grant No. 93-01-861, TEFIS computer library of thermophysical properties of matter).Deceased.Institute of Mathematical Modeling, Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 11–31, April, 1995.