A thermodynamically consistent quasi-particle model without temperature-dependent infinity of the vacuum zero point energy

Abstract

In this paper, an improved quasi-particle model is presented. Unlike the previous approach of establishing quasi-particle model, we introduce a classical background field (it is allowed to depend on the temperature) to deal with the infinity of thermal vacuum energy which exists in previous quasi-particle models. After taking into account the effect of this classical background field, the partition function of quasi-particle system can be made well-defined. Based on this and following the standard ensemble theory, we construct a thermodynamically consistent quasi-particle model without the need of any reformulation of statistical mechanics or thermodynamical consistency relation. As an application of our model, we employ it to the case of (2+1) flavor QGP at zero chemical potential and finite temperature and obtain a good fit to the recent lattice simulation results of S. Borsanyi et al. A comparison of the result of our model with early calculations using other models is also presented. It is shown that our method is general and can be generalized to the case where the effective mass depends not only on the temperature but also on the chemical potential.

Chiral phase transition with a chiral chemical potential in the framework of Dyson-Schwinger equations

“…However, thanks to the complicated non-Abelian feature of QCD itself, it is so difficult to have a thorough understanding of the mechanisms of DCSB and confinement, especially in the interesting nonperturbative region, where quarks and gluons are strongly coupled to each other and the related processes have small momentum transfer (or, equivalently, the coupling constant becomes large and running). In this case nowadays, people often in some sense have to resort to various effective models to study them phenomenologically, such as the chiral perturbation theory [1][2][3][4][5], the global color symmetry model [6][7][8][9][10], the quasiparticle model [11][12][13][14][15][16][17][18], the QCD sum rules [19][20][21][22], the Nambu-Jona-Lasinio (NJL) model and the related Polyakov-loop-extended Nambu-Jona-Lasinio (PNJL) model [23][24][25][26][27][28][29][30][31][32][33][34], lattice QCD [35][36][37], and the DysonSchwinger equations (DSEs) [38][39][40][41][42][43]…”

Baryon number fluctuations in quasi-particle model

“…One should pay attention to this reformulation, which in fact is based on mathematical identities involving derivatives with respect to temperature and chemical potentials, used to redefine the average energy density and the number density, respectively. The qQGP model with reformulated SM by Gorenstein and Yang has been studied by various groups [10][11][12][26][27][28][29][30][31]. On the other hand Bannur put forward another method, which skips the thermodynamic inconsistency by avoiding derivatives and instead uses the original definition of all thermodynamic quantities [32].…”

Study of rotational quark stars and hybrid stars based on the latest equation of state and observation data

“…Indeed, these parameters are obtained by fitting the Lattice QCD (LQCD) data in the case of finite temperature and zero chemical potential (for example, they were X = 6.6 and Ts = -0.8877. by fitting LQCD data at finite temperature in Ref. [16]). However, because of insufficient LQCD data on dense, strongly interacting matter, the phenomenological parameters of the quasiparticle model at zero temperature, and finite chemical potential have some uncertainties.…”

“…The quasiparticle model with a few fitting *zonghs@nju.edu.cn parameters has been widely used to reproduce the proper ties of the quark-gluon plasma and the deconfined quark matter [15]. In this work, we attempt to utilize an improved quasiparticle model [16,17] to obtain the EOS of QCD and to fit the latest empirical data. We then use this model to study the conversion from a NS to a quark star.…”