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In this paper we consider a metric with hyperscaling violation on black brane background. In this background we calculate the ratio of shear viscosity to entropy density with hydrodynamics information. The calculation of this quantity lead…

High Energy Physics - Theory · Physics 2015-06-19 Jafar Sadeghi , Ali Asadi

Among the key features of hot and dense QCD matter produced in ultra-relativistic heavy-ion collisions at RHIC is its very low shear viscosity, indicative of the properties of a near-ideal fluid, and a large opacity demonstrated by jet…

Nuclear Theory · Physics 2010-12-09 John Fuini , Nasser S. Demir , Dinesh K. Srivastava , Steffen A. Bass

We investigate the effects of baryon chemical potential \mu on the shear viscosity coefficient \eta and the viscosity to entropy density ratio \eta/s of a pion-nucleon gas mixture. We find that \eta is an increasing function of T and \mu,…

High Energy Physics - Phenomenology · Physics 2008-11-26 K. Itakura , O. Morimatsu , H. Otomo

The ratio of the shear viscosity to the entropy density is calculated for non-extremal Gauss-Bonnet (GB) black holes coupled to Born-Infeld (BI) electrodynamics in $5$ dimensions. The result is found to get corrections from the BI parameter…

High Energy Physics - Theory · Physics 2017-09-19 Saurav Das , Sunandan Gangopadhyay , Debabrata Ghorai

We have calculated the shear viscosity of pion medium, where propagating pion has some finite thermal width due to interaction with the low mass resonances, $\sigma$ and $\rho$. With the help of standard thermal field theoretical technique,…

Nuclear Theory · Physics 2017-09-12 Sabyasachi Ghosh , Gastao Krein , Saurav Sarkar

The ratio of shear viscosity to entropy density, $\eta/s$, is computed in various holographic geometries that break translation invariance (but are isotropic). The shear viscosity does not have a hydrodynamic interpretation in such…

High Energy Physics - Theory · Physics 2016-04-20 Sean A. Hartnoll , David M. Ramirez , Jorge E. Santos

We calculate the transport coefficient of hadronic matter in the presence of temperature and magnetic field using the linear sigma model. In the relaxation time approximation, we estimate the shear viscosity over entropy density $\eta/s$.…

High Energy Physics - Phenomenology · Physics 2022-06-22 Ritesh Ghosh , Najmul Haque

Through model-to-data comparisons from heavy-ion collisions, it has been shown that the Quark Gluon Plasma has an extremely small shear viscosity at vanishing densities. At large baryon densities, significantly less is known about the…

High Energy Physics - Phenomenology · Physics 2025-06-12 Isabella Danhoni , Jordi Salinas San Martin , Jacquelyn Noronha-Hostler

In this perspective review, we present a concise yet multifaceted overview of the pivotal role played by the the shear viscosity to entropy density ratio across various physical contexts. After summarizing some of the main aspects of the…

General Relativity and Quantum Cosmology · Physics 2025-09-09 Marilù Chiofalo , Dario Grasso , Stefano Liberati , Massimo Mannarelli

Shear viscosity of the gluon plasma in SU(3) YM theory is calculated nonperturbatively, within the stochastic vacuum model. The result for the ratio of the shear viscosity to the entropy density, proportional to the squared chromo-magnetic…

High Energy Physics - Phenomenology · Physics 2009-05-21 Dmitri Antonov

We consider the shear viscosity of a system of quarks and its ratio to the entropy density above the critical temperature for deconfinement. Both quantities are derived and computed for different modeling of the quark self-energy, also…

High Energy Physics - Phenomenology · Physics 2008-11-26 W. M. Alberico , S. Chiacchiera , H. Hansen , A. Molinari , M. Nardi

We report a calculation of the shear viscosity in a relativistic multicomponent meson gas as a function of temperature and chemical potentials. We approximately solve the Uehling-Uhlenbeck transport equation of kinetic theory, appropriate…

High Energy Physics - Phenomenology · Physics 2009-11-10 Antonio Dobado , Felipe J. Llanes-Estrada

This review highlights some of the lessons that the holographic gauge/gravity duality has taught us regarding the behavior of the shear viscosity to entropy density in strongly coupled field theories. The viscosity to entropy ratio has been…

High Energy Physics - Theory · Physics 2015-03-19 Sera Cremonini

We have evaluated the shear viscosity of pion gas taking into account its scattering with the low mass resonances, $\sigma$ and $\rho$ during propagation in the medium. The thermal width (or collisional rate) of the pions is calculated from…

Nuclear Theory · Physics 2014-04-08 Sabyasachi Ghosh , Gastão Krein , Sourav Sarkar

We compute the shear viscosity in the supersymmetric Yang-Mills theory dual to the STU background. This is a thermal gauge theory with a chemical potential. The quotient of the shear viscosity over the entropy density exhibits no deviation…

High Energy Physics - Theory · Physics 2009-11-11 J. Mas

We calculate the shear viscosity of field theories with gravity duals of Gauss-Bonnet gravity with a non-trivial dilaton using AdS/CFT. We find that the dilaton filed has a non-trivial contribution to the ratio of shear viscosity over…

High Energy Physics - Theory · Physics 2009-03-24 Rong-Gen Cai , Zhang-Yu Nie , Nobuyoshi Ohta , Ya-Wen Sun

Equilibration of highly excited baryon-rich matter is studied within the microscopic model calculations in A+A collisions at energies of BES, FAIR and NICA. It is shown that the system evolution from the very beginning of the collision can…

Nuclear Theory · Physics 2021-02-03 E. Zabrodin , L. Bravina , M. Teslyk , O. Vitiuk

We revisit the computation of the shear viscosity to entropy ratio $\eta/s$ at finite chemical potential in a holographic model that takes into account the quantum fluctuations in the IR region of near-extremal black branes. Such quantum…

High Energy Physics - Theory · Physics 2026-03-05 Sera Cremonini , Li Li , Xiao-Long Liu , Jun Nian

We compute the strong coupling limit of the shear viscosity for the N=4 super-Yang-Mill theory with a chemical potential. We use the five-dimensional Reissner-Nordstrom-anti-deSitter black hole, so the chemical potential is the one for the…

High Energy Physics - Theory · Physics 2008-11-26 Kengo Maeda , Makoto Natsuume , Takashi Okamura

In this study, we calculate the shear viscosity for rotating fermions with spin-half under conditions of high temperature and density. We employ the Kubo formalism, rooted in finite-temperature quantum field theory, to compute the field…

High Energy Physics - Phenomenology · Physics 2024-04-23 Sarthak Satapathy , Rajeev Singh , Pushpa Panday , Salman Ahamad Khan , Debarshi Dey