Hydrodynamics of R-charged black holes
Journal of High Energy Physics (2006) 1291-1309
Abstract:
We consider hydrodynamics of = 4 supersymmetric SU(Nc) Yang-Mills plasma at a nonzero density of R-charge. In the regime of large Nc and large 't Hooft coupling the gravity dual description involves an asymptotically Anti- de Sitter five-dimensional charged black hole solution of Behrnd, Cvetic and Sabra. We compute the shear viscosity as a function of chemical potentials conjugated to the three U(1)SO(6) R charges. The ratio of the shear viscosity to entropy density is independent of the chemical potentials and is equal to 1/4π. For a single charge black hole we also compute the thermal conductivity, and investigate the critical behavior of the transport coefficients near the boundary of thermodynamic stability. © SISSA 2006.Sound waves in strongly coupled non-conformal gauge theory plasma
Nuclear Physics B 733:1-2 (2006) 160-187
Abstract:
Using gauge theory/gravity duality we study sound wave propagation in strongly coupled non-conformal gauge theory plasma. We compute the speed of sound and the bulk viscosity of N = 2* supersymmetric SU(Nc) Yang-Mills plasma at a temperature much larger than the mass scale of the theory in the limit of large Nc and large 't Hooft coupling. The speed of sound is computed both from the equation of state and the hydrodynamic pole in the stress-energy tensor two-point correlation function. Both computations lead to the same result. Bulk viscosity is determined by computing the attenuation constant of the sound wave mode. © 2005 Elsevier B.V. All rights reserved.Quasinormal modes and holography
Physical Review D - Particles, Fields, Gravitation and Cosmology 72:8 (2005)
Abstract:
Quasinormal frequencies of electromagnetic and gravitational perturbations in asymptotically anti-de Sitter spacetime can be identified with poles of the corresponding real-time Green's functions in a holographically dual finite temperature field theory. The quasinormal modes are defined for gauge-invariant quantities which obey an incoming-wave boundary condition at the horizon and a Dirichlet condition at the boundary. As an application, we explicitly find poles of retarded correlation functions of R-symmetry currents and the energy-momentum tensor in strongly coupled finite temperature N=4 supersymmetric SU(Nc) Yang-Mills theory in the limit of large Nc. © 2005 The American Physical Society.The silence of the little strings
Journal of High Energy Physics (2005) 731-755
Abstract:
We study the hydrodynamics of the high-energy phase of Little String Theory. The poles of the retarded two-point function of the stress energy tensor contain information about the speed of sound and the kinetic coefficients, such as shear and bulk viscosity. We compute this two-point function in the dual string theory and analytically continue it to lorentzian signature. We perform an independent check of our results by the lorentzian supergravity calculation in the background of non-extremal NS5-branes. The speed of sound vanishes at the Hagedorn temperature. The ratio of shear viscosity to entropy density is equal to the universal value 1/4π and does not receive α′ corrections. The ratio of bulk viscosity to entropy density equals 1/10π. We also compute the R-charge diffusion constant. In addition to the hydrodynamic singularities, the correlators have an infinite series of finite-gap poles, and a massless pole with zero attenuation. © SISSA 2005.Viscosity in strongly interacting quantum field theories from black hole physics
Physical Review Letters 94:11 (2005)