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We consider $O(N)$ $g\varphi^4$ theory with the coupling $g$ being large, and calculate shear viscosity to entropy density ratio ($\eta/s$). The final result for $\eta/s$ has a form remarkably similar to that obtained from string theory…

High Energy Physics - Phenomenology · Physics 2016-05-23 Namit Mahajan

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

In the present paper, based on the principles of gauge/gravity duality we analytically compute the shear viscosity to entropy ratio corresponding to the superfluid phase in Einstein Gauss-Bonnet gravity. From our analysis we note that the…

High Energy Physics - Theory · Physics 2015-03-19 Arpan Bhattacharyya , Dibakar Roychowdhury

We present the first ab initio determination of the shear viscosity eta of the Unitary Fermi Gas, based on finite temperature quantum Monte Carlo calculations and the Kubo linear-response formalism. We determine the temperature dependence…

Quantum Gases · Physics 2012-07-16 Gabriel Wlazłowski , Piotr Magierski , Joaquín E. Drut

We compute the shear viscosity, $\eta$, at general temperatures $T$, in a BCS-BEC crossover scheme which is demonstrably consistent with conservation laws. The study of $\eta$ is important because it constrains microscopic theories by…

Quantum Gases · Physics 2011-08-04 H. Guo , D. Wulin , C. C. Chien , K. Levin

The shear viscosity of hot nuclear matter is investigated by using the mean free path method within the framework of IQMD model. Finite size nuclear sources at different density and temperature are initialized based on the Fermi-Dirac…

Nuclear Theory · Physics 2014-04-29 D. Q. Fang , Y. G. Ma , C. L. Zhou

Eighty years ago Eyring proposed that the shear viscosity of a liquid, $\eta$, has a quantum limit $\eta \gtrsim n\hbar$ where $n$ is the density of the fluid. Using holographic duality and the AdS/CFT correspondence in string theory…

Strongly Correlated Electrons · Physics 2015-09-30 Nandan Pakhira , Ross H. McKenzie

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

The shear viscosity $\eta$ has been calculated by using the Green-Kubo relation in the framework of a partonic transport approach solved at cascade level. We compare the numerical results for $\eta$ obtained from the Green-Kubo correlator…

Nuclear Theory · Physics 2015-09-01 S. Plumari , A. Puglisi , F. Scardina , V. Greco

Within a Boltzmann transport model, we demonstrate correlation between stopping observables and shear viscosity in central nuclear collisions at intermediate energies (on the order of 10 to 1000 MeV/nucleon). The correlation allows us to…

Nuclear Theory · Physics 2019-03-27 Brent Barker , Pawel Danielewicz

We reexamine the possibility of employing the viscosity over entropy density ratio as a diagnostic tool to identify a phase transition in hadron physics to the strongly coupled quark-gluon plasma and other circumstances where direct…

High Energy Physics - Phenomenology · Physics 2009-12-30 Antonio Dobado , Felipe J. Llanes-Estrada , Juan M. Torres-Rincon

We discuss a detailed study of the variation of shear viscosity, $\eta$, with temperature and baryon chemical potential within the framework of Polyakov$-$Nambu$-$Jona-Lasinio model. $\eta$ is found to depend strongly on the spectral width…

High Energy Physics - Phenomenology · Physics 2015-03-11 Sanjay K. Ghosh , Sibaji Raha , Rajarshi Ray , Kinkar Saha , Sudipa Upadhaya

We study the influence of a temperature-dependent shear viscosity over entropy density ratio $\eta/s$, different shear relaxation times $\tau_\pi$, as well as different initial conditions on the transverse momentum spectra of charged…

Nuclear Theory · Physics 2013-05-30 H. Niemi , G. S. Denicol , P. Huovinen , E. Molnár , D. H. Rischke

We consider an effective field theory description of beyond-quasi-particle excitations aiming to associate the transport properties of the system with the spectral density of states. Tuning various properties of the many-particle…

High Energy Physics - Phenomenology · Physics 2016-03-30 M. Horváth , A. Jakovác

The shear viscosity to entropy ratio ($\eta/s$) is estimated for the hot and dense QCD matter created in Au+Au collisions at RHIC ($\sqrt{s_{NN}}=200$ GeV). A very low value is found $\eta/s \sim 0.1$, which is close to the conjectured…

Based on IBUU simulations calibrated by previous efforts of the transport model evaluation project, we have studied the specific shear viscosity $\eta/s$ of nuclear matter in the spinodal region using the Green-Kubo method. With the…

Nuclear Theory · Physics 2023-03-03 Lei-Ming Hua , Jun Xu

We study hydrodynamic fluctuations in a non-relativistic fluid. We show that in three dimensions fluctuations lead to a minimum in the shear viscosity to entropy density ratio $\eta/s$ as a function of the temperature. The minimum provides…

Quantum Gases · Physics 2013-03-14 Clifford Chafin , Thomas Schaefer

The new state of matter produced at Relativistic Heavy Ion Collider reveals a strongly coupled quark-gluon plasma with an extremely small shear viscosity to entropy density ratio eta/s. We calculate the eta/s of an equilibrated hadron…

Nuclear Theory · Physics 2014-11-20 Subrata Pal

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

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