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One of the most striking results from the Relativistic Heavy Ion Collider is the strong elliptic flow. This review summarizes what is observed and how these results are combined with reasonable theoretical assumptions to estimate the shear…

Nuclear Theory · Physics 2016-12-21 Derek A. Teaney

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 investigate the temperature dependence of the shear viscosity to entropy density ratio $\eta/s$ using a piecewise linear parametrization. To determine the optimal values of the parameters and the associated uncertainties, we perform a…

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…

We study the gravitational Dirichlet problem in AdS spacetimes with a view to understanding the boundary CFT interpretation. We define the problem as bulk Einstein's equations with Dirichlet boundary conditions on fixed timelike cut-off…

High Energy Physics - Theory · Physics 2015-05-28 Daniel K. Brattan , Joan Camps , R. Loganayagam , Mukund Rangamani

We give a breezy, qualitative overview of some of our recent results on studying jet stopping in strongly-coupled plasmas using gauge-gravity duality. Previously, people have found that the maximum stopping distance in such plasmas scales…

High Energy Physics - Theory · Physics 2015-05-28 Peter Arnold , Diana Vaman

There has been recent progress on computing real-time equilibrium 3-point functions in finite-temperature strongly-coupled N=4 super Yang-Mills (SYM). In this paper, we show an example of how to carry out a similar analysis for a 4-point…

High Energy Physics - Theory · Physics 2015-05-30 Peter Arnold , Diana Vaman

Although the AdS/CFT correspondence is rigorous only for an infinite $N \to \infty$ stack of D3-branes, it can be fruitfully studied for finite $N$ as a source of gauge structures and choices for chiral fermions and complex scalars which…

High Energy Physics - Theory · Physics 2009-10-31 Paul H. Frampton

The remarkably small shear viscosity to entropy density ratio $\eta/s < 0.5$ of the quark-gluon plasma (QGP) is a key insight from heavy ion experiments. Nonetheless, the basic understanding of this `observable' still seems to be…

High Energy Physics - Phenomenology · Physics 2018-08-15 Greg Jackson , Andre Peshier

We substantiate a covariant proposal for the holographic reflected entropy in $CFT$s dual to non-static $AdS$ geometries from the bulk extremal entanglement wedge cross section in the literature with explicit computations in the…

High Energy Physics - Theory · Physics 2022-12-27 Mir Afrasiar , Himanshu Chourasiya , Vinayak Raj , Gautam Sengupta

In this contribution we summarize recent progress in understanding the shear viscosity of strongly correlated dilute Fermi gases. We discuss predictions from kinetic theory, and show how these predictions can be tested using recent…

Nuclear Theory · Physics 2015-05-20 Thomas Schaefer

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

We explore the constraints imposed on higher curvature corrections of the Lovelock type due to causality restrictions in the boundary of asymptotically AdS space-time. In the framework of AdS/CFT, this is related to positivity of the energy…

High Energy Physics - Theory · Physics 2014-11-20 Xian O. Camanho , Jose D. Edelstein

We review the computation of scattering amplitudes of planar maximally super-symmetric Yang-Mills at strong coupling. By using the AdS/CFT duality the problem boils down to the computation of the area of certain minimal surfaces on AdS. The…

High Energy Physics - Theory · Physics 2015-05-20 Luis F. Alday

The lower bound of the shear viscosity to entropy density ratio is examined using an exact representation of the ratio through the density of states. It is shown that the lower bound in a generic physical system is not universal, its value…

High Energy Physics - Theory · Physics 2014-11-20 A. Jakovac

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

We compute the bulk entanglement entropy of a massive scalar field in a Poincare AdS with the Dirichlet and Neumann boundary condition when we trace out a half space. Moreover, by taking into account the quantum back reaction to the minimal…

High Energy Physics - Theory · Physics 2016-01-25 Taiki Miyagawa , Noburo Shiba , Tadashi Takayanagi

We calculate shear viscosity to entropy density ratio in presence of four derivative (with coefficient $\alpha'$) and six derivative (with coefficient $\alpha'^2$) terms in bulk action. In general, there can be three possible four…

High Energy Physics - Theory · Physics 2009-07-22 Nabamita Banerjee , Suvankar Dutta

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 compute the shear viscosity of the unitary Fermi gas above the superfluid transition temperature, using a diagrammatic technique that starts from the exact Kubo formula. The formalism obeys a Ward identity associated with scale…

Quantum Gases · Physics 2011-02-01 Tilman Enss , Rudolf Haussmann , Wilhelm Zwerger