The running of the QCD coupling in the effective mass causes thermodynamic inconsistency problem in the conventional quasiparticle model. We provide a novel treatment which removes the inconsistency by an effective bag constant. The chemical potential dependence of the renormalization subtraction point is constrained by the Cauchy condition in the chemical potential space. The stability and microscopic properties of strange quark matter are then studied within the completely self-consistent quasiparticle model, and the obtained equation of state of quark matter is applied to the investigation of strange stars. It is found that our improved model can describe well compact stars with mass about two times the solar mass, which indicates that such massive compact stars could be strange stars.
Zhen Yan LuGuang Xiong PengJian Feng XuShi Peng Zhang
We report on our results about spontaneous chiral symmetry breaking for quark matter in the background of static and homogeneous parallel electric field,E,and magnetic field,B.A Nambu–Jona–Lasinio model is used to compute the dependence of the chiral condensate at finite temperature,E and B.We study the effect of this background on inverse catalysis of chiral symmetry breaking for E and B of the same order of magnitude.We also consider the effect of equilibration of chiral density,n_5,produced by axial anomaly on the critical temperature.The equilibration of n_5 allows for the introduction of the chiral chemical potential,u_5,which is computed selfconsistently as a function of temperature and field strength.We find that even if the chiral medium is produced by the fields the thermodynamics,with particular reference to the inverse catalysis induced by the external fields,it is not very affected by n_5 at least if the average u_5,at equilibrium is not too large.
We investigated the properties of strange quark matter in an external strong magnetic field with both confinement and leading-order perturbative interactions considered. It was found that the leading-order perturbative interaction can stiffen the equation of state of magnetized quark matter, while the magnetic field lowers the minimum energy per baryon. By solving the Tolman–Oppenheimer–Volkoff equations, we obtain the internal structure of strange stars. The maximum mass of strange stars can be as large as 2 times the solar mass.
We study the properties of two-flavor quark matter in the equivparticle model.A new quark mass scaling at finite temperature is proposed and applied to the thermodynamics of two-flavor quark matter.It is found that the perturbative interaction has strong effect on quark matter properties at finite temperature and high density.The pressure at the minimum free energy per baryon is exactly zero.With increasing temperature,the energy per baryon increases,while the free energy per baryon decreases.
The equation of state of symmetric nuclear matter is studied with an equivalent mass model.The equivalent mass of a nucleon has been expanded to order 4 in density.We first determine the first-order expansion coefficient in the quantum hadron dynamics,then calculate the coefficients of the second to fourth order for the given binding energy and incompressibility at the normal nuclear saturation density.It is found that there appears a density isomeric state if the incompressibility is smaller than a critical value.The model dependence of the conclusion has also been checked by varying the first-order coefficient.
We report our recent work on mean-field potential effects on the elliptic flows of matters and antimatters in heavy ion collisions leading to the production of a baryon-rich matter.Within the framework of a multiphase transport(AMPT) model that includes both initial partonic and final hadronic interactions,we have found that including mean-field potentials in the hadronic phase leads to a splitting of the elliptic flows of particles and their antiparticles,providing thus a plausible explanation of the different elliptic flows between p and anti-p,K+and K-,and π+ and π- observed by the STAR Collaboration in the Beam Energy Scan(BES) program at the Relativistic Heavy Ion Collider(RHIC).Using a partonic transport model based on the Nambu-Jona-Lasinio(NJL) model,we have also studied the effect of scalar and vector mean fields on the elliptic flows of quarks and antiquarks in these collisions.Converting quarks and antiquarks at hadronization to hadrons via the quark coalescence model,we have found that the elliptic flow differences between particles and antiparticles also depend on the strength of the quark vector coupling in baryon-rich quark-gluon plasma,providing thus the possibility of extracting information on the latter's properties from the BES program at RHIC.
KO ChemingCHEN LiewenGRECO VincenzoLI FengLIN ZiweiPLUMARI SalvatoreSONG TaesooXU Jun
The properties of color-flavor locked strange quark matter in an external strong magnetic field are investigated in a quark model with density-dependent quark masses.Parameters are determined by stability arguments.It is found that the minimum energy per baryon of the color-flavor locked(MCFL)matter decreases with increasing magnetic-field strength in a certain range,which makes MCFL matter more stable than other phases within a proper magnitude of the external magnetic field.However,if the energy of the field itself is added,the total energy per baryon will increase.
Considering the effect of one-gluon-exchange interaction between quarks,the color-flavor locked strange quark matter and strange stars are investigated in a new quark mass density-dependent model.It is found that the color-flavor locked strange quark matter can be more stable if the one-gluon-exchange effect is included.The lower density behavior of the sound velocity in this model is different from the previous results.Moreover,the new equation of state leads to a heavier acceptable maximum mass,supporting the recent observation of a compact star mass as large as about 2 times the solar mass.
Direct extrapolation of the strong interaction between quarks in pure perturbative calculation has a problem of thermodynamic inconsistency. A new term determined by thermodynamic consistency requirement could resolve it. This new term plays an important role at lower density in describing the equation of state of quark matter, while it is negligible at high density. Accordingly, the density behavior of the sotmd velocity becomes more reasonable, and the maximum mass of quark stars can be as large as two times the solar mass.
The properties of strangelets at zero temperature with a new quark model that includes both the confinement and one-gluonexchange interactions is studied in a fully self-consistent method.The charge and parameter dependence of the stability of strangelets are discussed.It is found that the one-gluon-exchange interaction lowers the energy of a strangelet,and consequently allows the strangelet to be absolutely stable.The stable strangelet radius in the present model is smaller in comparison with the absence of one-gluon-exchange interaction,and can thus be much less than that of a normal nucleus with the same baryon number,according to the strength of the confinement and one-gluon-exchange interactions.
