Equation of state of deconfined matter within a dynamical quasiparticle description

A simple quasiparticle model, motivated by lowest-order perturbative QCD, is proposed. It is applied to interpret the lattice QCD equation of state. A reasonable reproduction of the lattice data is obtained. In contrast to existing quasiparticle models, the present model is formulated in dynamical rather than thermodynamical terms, and is easily applicable to a system with finite baryon density. In particular, the model simulates the confinement property.

Figure 1

Pressure normalized by $T^4$ as a function of $T/T_c$ at $\mu =0$. The solid line corresponds to “1-loop” calculation with the overall normalization factor of 0.9. The dashed line represents the “2-loop” calculation. The $(2+1)$-flavor lattice data [2] are displayed by open circles, and the 2-flavor lattice data [1]—by gray band.

Figure 2

$\Delta P=P(T,\mu )-P(T,\mu =0)$ normalized by $T^4$ as a function of $T/T_c$ at $\mu =100$, 210, 330, 410, 530 MeV (from bottom to top) within the “1-loop” (upper panel) and “2-loop” (lower panel) calculations. The $(2+1)$-flavor lattice data are from 2.

Figure 3

Interaction measure, $\epsilon -3P$, normalized by $T^4$ as a function of $T/T_c$ at $\mu =0$, 330, 530 MeV (which are hardly distinguishable between each other) within the “1-loop” (upper panel) and “2-loop” (lower panel) calculations. The $(2+1)$-flavor lattice data [2] for different $\mu =0$, 330, 530 MeV are displayed by open circles, diamonds, and full circles, respectively, similarly to other figures.

Figure 4

Baryon density normalized by $T^3$ as a function of $T/T_c$ at $\mu =100$, 210, 330, 410, 530 MeV (from bottom to top) within the “1-loop” (upper panel) and “2-loop” (lower panel) calculations. The $(2+1)$-flavor lattice data are from 2.

Figure 5

Effective masses of $u$ and $d$ quarks (upper panel) and $s$ quark (lower panel) as functions of $T/T_c$ at $\mu =0$, 900, 1500 MeV (from bottom to top). Solid and dashed lines correspond to “1-loop” and “2-loop” calculations, respectively.

Figure 6

Effective gluon mass (upper panel) and coupling constant squared (lower panel) as a function of $T/T_c$ at $\mu =0$, 900, 1500 MeV (from bottom to top in upper panel, and from top to bottom in lower panel). Solid and dashed lines correspond to “1-loop” and “2-loop” calculations, respectively.