Calculations of shear, bulk viscosities and electrical conductivity in the Polyakov-quark–meson model

Abstract

We have calculated different transport coefficients like shear, bulk viscosities and electrical conductivity of quark and hadronic matter within the framework of 2 flavor Polyakov-Quark-Meson model. For constant thermal widths of quarks and mesons, the temperature dependence of different transport coefficients reveals the thermodynamical phase space structure and their qualitative behavior are quite well in agreement with earlier works, based on other dynamical models. Besides the phase-space structure of quarks and mesons, their thermal width also have explicit temperature dependence. This dependence has been obtained here from the imaginary part of their respective self-energies at finite temperature. Due to the threshold conditions of their self energies, only some limited temperature regions of quark and hadronic phase are relevant for our numerical estimation of transport coefficients, which are grossly in agreement with some of the earlier results. An interesting outcome of the present analysis is that the quark relaxation time due to quark-meson loops can develop perfect fluid nature within a specific temperature range.

Electrical conductivity and relaxation via colored noise in a hadronic gas

“…Their dynamics depends by Maxwell's equations on the electrical conductivity. This coefficient was computed in hadronic kinetic theory [27], partonic transport models [39,40], off-shell transport and dynamical quasiparticle models [41][42][43][44], holography [45][46][47], lattice QCD [29,[48][49][50], Dyson-Schwinger calculations [51], in the Polyakov-extended quarkmeson model [52], semianalytic calculations within perturbative QCD [53][54][55], and also taking into account strong magnetic fields [56,57]. Closer to the systems we are considering in this work we mention semianalytical calculations in a pion gas using chiral perturbation theory with and without unitarization [33,58], in a pion gas using a sigma model with and without mediummodified interactions [59], in a sigma model with baryon interactions [60], and in resonance gas models [27,61].…”

In-medium effect on the thermodynamics and transport coefficients in the van der Waals hadron resonance gas

“…We also compare our result with the results of some earlier works. The orange dashed line and blue double-dotted-dashed line correspond to the estimation of λ=T 2 at μ B ¼ 0.1 GeV in the SU(3) NJL model [30] and in the SU(2) Polyakov quark meson (PQM) model [32], respectively. The red dotted line represents the result of the EVHRG model [51].…”

“…The transport coefficients in the medium composed of quasiparticles whose masses depend on the temperature and chemical potential can be derived by utilizing the relativistic kinetic theory under the relaxation time approximation [32,82,83]. The general expressions of shear viscosity (η), electrical conductivity (σ el ), and thermal conductivity (λ) can be written as [32,82]…”

“…[18], shear viscosity for pion gas has been obtained in the linear response theory using Kubo formulas. The shear viscosity for the hadronic phase has also been computed in the microscopic transport model (e.g., SMASH [19], the ultrarelativistic quantum molecular dynamics (UrQMD) model [20], B3D transport model [21], and PHSD [22]), excluded volume HRG (EVHRG) model [23][24][25], chiral perturbative theory (ChPT) [26][27][28], effective QCD models [29][30][31][32], quasiparticle theory [33,34], scaled hadron mass-couplings (SHMC) model [35], and so on. A few articles also deal with electrical conductivity in pure pion gas [27,36].…”

Electrical conductivity of hot Abelian plasma with scalar charge carriers

“…These correlators have to be calculated in finite temperature quantum field theory and the leading order result is obtained by the resummation of an infinite number of ladder diagrams. This approach was applied to the calculation of the transport coefficients in scalar field theory [16][17][18], in gauge theories [19,20] as well as in the effective models of quantum chromodynamics (QCD) such as the Nambu-Jona-Lasinio model [21,22], the lattice QCD [23], the Polyakov-Quark-Meson model [24] etc. Although it is the most general approach, applicable to any given field theory, it requires inventing ingenious resummation schemes, especially for the gauge theories, and therefore it is not very convenient.…”