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Time evolution of shear viscosity $\eta$, entropy density $s$, and their ratio $\eta / s$ in the central area of central gold-gold collisions at NICA energy range is studied within the UrQMD transport model. The extracted values of energy…

Nuclear Theory · Physics 2020-01-15 M. Teslyk , L. Bravina , O. Panova , O. Vitiuk , E. Zabrodin

The shear viscosity of an interacting pion gas is studied using the Kubo formalism as a microscopic description of thermal systems close to global equilibrium. We implement the skeleton expansion in order to approximate the retarded…

High Energy Physics - Phenomenology · Physics 2012-09-05 Robert Lang , Norbert Kaiser , Wolfram Weise

We present an ab initio determination of the shear viscosity for the unitary Fermi gas based on finite temperature quantum Monte Carlo (QMC) calculations and the Kubo linear-response formalism. The results are confronted with the bound for…

Quantum Gases · Physics 2013-08-02 Gabriel Wlazłowski , Piotr Magierski , Aurel Bulgac , Kenneth J. Roche

We explore in greater detail our investigations of shear diffusion in hyperscaling violating Lifshitz theories in arXiv:1604.05092 [hep-th]. This adapts and generalizes the membrane-paradigm-like analysis of Kovtun, Son and Starinets for…

High Energy Physics - Theory · Physics 2017-07-12 Kedar S. Kolekar , Debangshu Mukherjee , K. Narayan

We calculate the ratio of shear viscosity to entropy density for charged black branes in third order Lovelock theory. For chargeless black branes, the result turns out to be consistent with the prediction made in $\rm arXiv:0808.3498[\rm…

High Energy Physics - Theory · Physics 2009-11-17 Xian-Hui Ge , Sang-Jin Sin , Shao-Feng Wu , Guo-Hong Yang

The ratio of bulk to shear viscosity is expected to exhibit a different behaviour in weakly and in strongly coupled systems. This can be expressed by its dependence on the squared sound velocity. In the high temperature QCD plasma at small…

High Energy Physics - Phenomenology · Physics 2015-05-27 M. Bluhm , B. Kampfer , K. Redlich

The relation of the shear viscosity coefficient to the recently introduced transport rate is derived within relativistic kinetic theory. We calculate the shear viscosity over entropy ratio \eta/s for a gluon gas, which involves elastic gg->…

Nuclear Theory · Physics 2008-11-26 Zhe Xu , Carsten Greiner

We show that the generalized second law of thermodynamics may shed much light on the mysterious Kovtun-Son-Starinets (KSS) bound on the ratio of viscosity to entropy density. In particular, we obtain the lower bound $\eta/s…

High Energy Physics - Theory · Physics 2009-10-12 Shahar Hod

The ratio between the shear viscosity and the entropy $\eta/s$ is considered a universal measure of the strength of interactions in quantum systems. This quantity was conjectured to have a universal lower bound $(1/4\pi)\hbar/k_{B}$, which…

Strongly Correlated Electrons · Physics 2021-07-07 Sang Wook Kim , Geo Jose , Bruno Uchoa

We compute the shear viscosity of weakly coupled N=4 supersymmetric Yang-Mills (SYM) theory. Our result for [eta/s], the viscosity to entropy-density ratio, is many times smaller than the corresponding weak-coupling result in QCD. This…

High Energy Physics - Phenomenology · Physics 2008-11-26 Simon C. Huot , Sangyong Jeon , Guy D. Moore

We study the properties of the shear viscosity coefficient of quark matter near the chiral phase transition at finite temperature and chemical potential, and the kinds of high temperature, high density and strong magnetic field background.…

High Energy Physics - Phenomenology · Physics 2023-12-29 Yi-Wei Qiu , Sheng-Qin Feng , Xue-Qiang Zhu

We investigate the low-temperature behavior of the ratio between the shear viscosity \eta and the entropy density s in the unitary Fermi gas by using a model based on the zero-temperature spectra of both bosonic collective modes and…

Quantum Gases · Physics 2011-11-08 Luca Salasnich , Flavio Toigo

We prove the universality of the Chern-Simons diffusion rate - a crucial observable for the chiral magnetic effect - in a large class of planar strongly correlated gauge theories with dual string description. When the effects of anomalies…

High Energy Physics - Theory · Physics 2018-12-05 Francesco Bigazzi , Aldo L. Cotrone , Flavio Porri

Transport coefficeints, in particular the shear viscosity to entropy density ratio is studied in systems where the small-width quasiparticle assumption is not valid. It is found that $\eta/s$ has no unversal lower bound, the minimal value…

High Energy Physics - Phenomenology · Physics 2017-08-23 A. Jakovac

The shear and the bulk viscosities of the hadron gas at low temperatures are studied in the model with constant elastic cross sections being relativistic generalization of the hard spheres model. One effective radius ${r=0.4 fm}$ is chosen…

High Energy Physics - Phenomenology · Physics 2015-03-19 Oleg N. Moroz

We compute the bulk viscosity of a gas of pions at temperatures below the QCD crossover temperature, for the physical value of pion mass, to lowest order in chiral perturbation theory. Bulk viscosity is controlled by number-changing…

High Energy Physics - Phenomenology · Physics 2011-07-19 Egang Lu , Guy D. Moore

We investigate two transport coefficients, shear viscosity and conductivity, in a non-relativistic boundary filed theory without hyperscaling symmetry, which is dual to a bulk charged hyperscaling violating black brane. Employing matching…

High Energy Physics - Theory · Physics 2017-09-13 Xiao-Mei Kuang , Jian-Pin Wu

We present a detailed analysis of the contribution of small-angle Nambu-Goldstone boson (phonon) collisions to the shear viscosity, $\eta$, in a superfluid atomic Fermi gas close to the unitarity limit. We show that the experimental values…

Quantum Gases · Physics 2013-07-02 Massimo Mannarelli , Cristina Manuel , Laura Tolos

The shear viscosity of a two-component Fermi gas in the normal phase is calculated as a function of temperature in the unitarity limit, taking into account strong-coupling effects that give rise to a pseudogap in the spectral density for…

Statistical Mechanics · Physics 2008-11-26 G. M. Bruun , H. Smith

The temperature dependence of the chiral condensate in isospin-symmetric nuclear matter at varying baryon densities is investigated starting from a realistic free energy density of the correlated nuclear many-body system. The framework is…

Nuclear Theory · Physics 2011-04-15 S. Fiorilla , N. Kaiser , W. Weise