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The universal lower bound of the ratio of shear viscosity to entropy density is suggested by the string theory and gauge duality for any matter. We examined the ratio of shear viscosity to entropy density for viscous accretion flow towards…

General Relativity and Quantum Cosmology · Physics 2019-06-28 Sandip Dutta , Ritabrata Biswas

Based on the first principle calculation, a Lagrangian for the system describing quarks, gluons, and their interactions, is constructed. Ascribed to the existence of dissipative behavior as a consequence of strong interaction within…

High Energy Physics - Phenomenology · Physics 2015-05-20 T. P. Djun , B. Soegijono , T. Mart , L. T. Handoko

We calculate the shear viscosity of strongly coupled field theories dual to Gauss-Bonnet gravity at zero temperature with nonzero chemical potential. We find that the ratio of the shear viscosity over the entropy density is $1/4\pi$, which…

High Energy Physics - Theory · Physics 2010-05-12 Rong-Gen Cai , Yan Liu , Ya-Wen Sun

We calculate the shear viscosity and anomalous baryon number violation rate in quantum field theories at finite temperature having gravity duals with hyperbolic horizons. We find the explicit dependence of these quantities on the…

High Energy Physics - Theory · Physics 2015-05-13 George Koutsoumbas , Eleftherios Papantonopoulos , George Siopsis

We determine the shear viscosity of the ultracold Fermi gas at unitarity in the normal phase using hydrodynamic expansion data. The analysis is based on a generalized fluid dynamic framework which ensures a smooth transition between the…

Quantum Gases · Physics 2017-08-16 Marcus Bluhm , Jiaxun Hou , Thomas Schaefer

It has been conjectured, on the basis of the gauge-gravity duality, that the ratio of the shear viscosity to the entropy density should be universally bounded from below by 1/ 4 pi in units of the Planck constant divided by the Boltzmann…

High Energy Physics - Theory · Physics 2014-11-20 Ram Brustein , A. J. M. Medved

We classify all the six derivative Lagrangians of gravity, whose traced field equations are of second or third order, in arbitrary dimensions. In the former case, the Lagrangian in dimensions greater than six, reduces to an arbitrary linear…

General Relativity and Quantum Cosmology · Physics 2010-12-28 Julio Oliva , Sourya Ray

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

We investigate the collision energy dependence of shear viscosity over the entropy density ratio $\eta/s$ in Au+Au collisions at $\sqrt{s_{NN}}=19.6, 39$, and $62.4$ GeV, using Bayesian statistical analysis and Gaussian process emulators to…

Nuclear Theory · Physics 2016-10-04 Jussi Auvinen , Jonah E. Bernhard , Steffen A. Bass

Based on the finite-temperature AdS/CFT correspondence, we calculate the ratio of shear viscosity to entropy density in any Lovelock theories to any order. Our result shows that any Lovelock correction terms except the Gauss-Bonnet term…

High Energy Physics - Theory · Physics 2010-04-30 Fu-Wen Shu

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

The shear ($\eta$) and bulk ($\zeta$) viscosities are calculated in a quasiparticle relaxation time approximation. The hadron phase is described within the relativistic mean field based model with scaled hadron masses and couplings. The…

Nuclear Theory · Physics 2010-10-19 A. S. Khvorostukhin , V. D. Toneev , D. N. Voskresensky

We study the shear mode in the gauge/gravity correspondence at finite temperature. First, we confirm the general formula for the shear viscosity in an arbitrary background metric which includes a black hole in the fifth dimension. We then…

High Energy Physics - Theory · Physics 2008-11-26 J. I. Kapusta , T. Springer

The ratio of shear viscosity ($\eta$) to entropy density ($s$) for an equilibrated system is investigated in intermediate energy heavy ion collisions below 100$A$ MeV within the framework of the Boltzmann-Uehling-Uhlenbeck (BUU) model .…

Nuclear Theory · Physics 2011-09-01 S. X. Li , D. Q. Fang , Y. G. Ma , C. L. Zhou

We examine the structure of the shear viscosity to entropy density ratio eta/s in holographic theories of gravity coupled to a scalar field, in the presence of higher derivative corrections. Thanks to a non-trivial scalar field profile,…

High Energy Physics - Theory · Physics 2015-06-05 Sera Cremonini , Umut Gursoy , Phillip Szepietowski

Despite the viscosity of a fluid ranges over several orders of magnitudes and is extremely sensitive to microscopic structure and molecular interactions, it has been conjectured that its (opportunely normalized) minimum displays a universal…

High Energy Physics - Theory · Physics 2022-06-28 Matteo Baggioli , Li Li , Hao-Tian Sun

Near the horizon of a black brane in Anti-de Sitter (AdS) space and near the AdS boundary, the long-wavelength fluctuations of the metric exhibit hydrodynamic behaviour. The gauge-gravity duality then relates the boundary hydrodynamics for…

High Energy Physics - Theory · Physics 2009-03-27 Ram Brustein , A. J. M. Medved

The shear viscosity, eta, of a fermi gas with non-relativistic conformal symmetry in two spatial dimensions is investigated. We find that eta/s, s being the entropy density, diverges as a gas of free particles in this system. It is in…

High Energy Physics - Theory · Physics 2013-01-01 Jiunn-Wei Chen , Wen-Yu Wen

We consider strongly coupled gauge theory plasma with conserved global charges that allow for a dual gravitational description. We study the shear viscosity of the gauge theory plasma in the presence of chemical potentials for these…

High Energy Physics - Theory · Physics 2008-11-26 Paolo Benincasa , Alex Buchel , Roman Naryshkin

Second-order dissipative hydrodynamic equations for each component of a multi-component system are derived using the entropy principle. The shear viscosity of the whole system, appearing in the equation summed-up over all components, is…

High Energy Physics - Phenomenology · Physics 2011-03-24 Andrej El , Ioannis Bouras , Francesco Lauciello , Zhe Xu , Carsten Greiner