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A real-time thermal field theoretical calculation of shear viscosity has been described in the Kubo formalism for bosonic and fermionic medium. The two point function of viscous stress tensor in the lowest order provides one-loop skeleton…

Nuclear Theory · Physics 2014-04-21 Sabyasachi Ghosh

We calculate the shear relaxation times in four important simple monatomic model fluids: Lennard-Jones, Yukawa, soft-sphere and hard-sphere fluids. It is observed that in properly reduced units, the shear relaxation times exhibit…

Soft Condensed Matter · Physics 2024-12-11 S. A. Khrapak , A. G. Khrapak

We evaluate the ratio of the shear viscosity to the relaxation time of the shear flux above but near the critical temperature $T_c$ in SU(3) gauge theory on the lattice. The ratio is related to Kubo's canonical correlation of the…

High Energy Physics - Lattice · Physics 2013-03-26 Yasuhiro Kohno , Masayuki Asakawa , Masakiyo Kitazawa

Kinetic equations for quarks and gluons are solved numerically in the relaxation time approximation for the case of one-dimensional boost-invariant geometry. Quarks are massive and described by the Fermi-Dirac statistics, while gluons are…

High Energy Physics - Phenomenology · Physics 2018-03-07 Wojciech Florkowski , Ewa Maksymiuk , Radoslaw Ryblewski

Due to lowest possible quantum fluctuation, shear viscosity to entropy density ratio never reach to zero, rather has some lower bound (0.08 approx). Here, we have attempted to link our calculation, based on relaxation time approximation for…

High Energy Physics - Phenomenology · Physics 2020-01-24 Sarthak Satapathy , Jayanta Dey , Prashant Murmu , Sabyasachi Ghosh

We concentrate on calculation of the shear and bulk viscosities of the hadron gas. They define its dissipative dynamics and influence its experimentally measurable elliptic flow. Due to difficulty of this calculation the relaxation time…

High Energy Physics - Phenomenology · Physics 2016-01-01 O. Moroz

A theoretical framework for the calculation of shear and bulk viscosities of hadronic matter at finite temperature is presented. The framework is based on the quasi-particle picture. It allows for an arbitrary number of hadron species with…

Nuclear Theory · Physics 2011-02-01 P. Chakraborty , J. I. Kapusta

We probe the relation between shear induced structural relaxation and rheology in experiments on sheared two-dimensional foams. The relaxation time, which marks the crossover to diffusive bubble motion, is found to scale non-trivially with…

Soft Condensed Matter · Physics 2009-01-27 Matthias E. Möbius , Gijs Katgert , Martin van Hecke

Owing to the Kubo relation, the shear viscosities of pionic and nucleonic components have been evaluated from their corresponding retarded correlators of viscous stress tensor in the static limit, which become non-divergent only for the…

Nuclear Theory · Physics 2015-09-15 Sabyasachi Ghosh

Accurately describing liquids and their mixtures beyond equilibrium remains a significant challenge in modern chemical physics and physical chemistry, especially regarding the calculation of transport properties in liquid-phase systems.…

Soft Condensed Matter · Physics 2025-06-19 Yury A. Budkov , Nikolai N. Kalikin , Petr E. Brandyshev

In this work, we examine the effect of shear and bulk viscosities on elliptic flow by taking a realistic parameterization of the shear and bulk viscous coefficients, $\eta$ and $\zeta$, and their respective relaxation times, $\tau_{\pi}$…

Nuclear Theory · Physics 2014-11-20 G. S. Denicol , T. Kodama , T. Koide

Using Mathematica package, we derive analytical closed-form expressions for the shear and the bulk viscosity coefficients in multicomponent relativistic gases with constant cross sections, being the relativistic generalization for the hard…

Fluid Dynamics · Physics 2014-02-11 O. Moroz

A new approach to the dynamics of relaxation and kinetics of thermalization in a scalar field theory is presented that incorporates the relevant time scales through the resummation of hard thermal loops. An alternative derivation of the…

High Energy Physics - Phenomenology · Physics 2009-10-28 D. Boyanovsky , I. D. Lawrie , D. S. Lee

Deep in the Earth's crust, pressure exceeds one thousand times the atmospheric pressure. Water still flows under these conditions, but experiences dramatic changes in structure and fluidity. Using combined dynamic and inelastic light…

We study shear viscosity in weakly coupled hot pure gauge field QCD theory basing on transport theory and the Kubo formula using the closed time path formalism (CTP) of real time finite temperature field theory. We show that the viscosity…

High Energy Physics - Phenomenology · Physics 2007-05-23 Hou Defu

Assuming that the Hagedorn fluid composed of known particles and resonances with masses $m<2\,$GeV obeys the {\it first-order} theory (Eckart) of relativistic fluid, we discuss the transport properties of QCD confined phase. Based on the…

High Energy Physics - Phenomenology · Physics 2010-11-24 A. Tawfik , M. Wahba

The microscopic formulae of the bulk viscosity $\zeta $ and the corresponding relaxation time $\tau_{\Pi}$ in causal dissipative relativistic fluid dynamics are derived by using the projection operator method. In applying these formulae to…

Nuclear Theory · Physics 2011-02-23 Xu-Guang Huang , Takeshi Kodama , Tomoi Koide , Dirk H. Rischke

We discuss shear viscosity of the quark matter by using Kubo formula. The shear viscosity is calculated in the framework of the quasi-particle RPA for the Nambu-Jona-Lasinio model. We obtain a formula that the shear viscosity is expressed…

High Energy Physics - Phenomenology · Physics 2009-11-13 Masaharu Iwasaki , Hiromasa Ohnishi , Takahiko Fukutome

Shear $\eta$ and bulk $\zeta$ viscosities are calculated in a quasiparticle model within a relaxation time approximation for pure gluon matter. Below $T_c$ the confined sector is described within a quasiparticle glueball model. Particular…

Nuclear Theory · Physics 2015-03-17 A. S. Khvorostukhin , V. D. Toneev , D. N. Voskresensky

We discuss the shear viscosity of the quark matter by using the Kubo-Mori formula. It is found that the shear viscosity is expressed in terms of the quark spectral function. If the spectral function is approximated by a modified…

High Energy Physics - Phenomenology · Physics 2007-05-23 Masaharu Iwasaki , Hiromasa Ohnishi , Takahiko Fukutome