TY - JOUR

T1 - Sound damping constant for generalized theories of gravity

AU - Brustein, Ram

AU - Medved, A. J.M.

PY - 2009/6/19

Y1 - 2009/6/19

N2 - The near-horizon metric for a black brane in anti-de Sitter space and the metric near the AdS boundary both exhibit hydrodynamic behavior. We demonstrate the equivalence of this pair of hydrodynamic systems for the sound mode of a conformal theory. This is first established for Einstein's gravity, but we then show how the sound damping constant will be modified from its Einstein form for a generalized theory. The modified damping constant is expressible as the ratio of a pair of gravitational couplings that are indicative of the sound-channel class of gravitons. This ratio of couplings differs from both that of the shear diffusion coefficient and the shear viscosity to entropy ratio. Our analysis is mostly limited to conformal theories, but suggestions are made as to how this restriction might eventually be lifted.

AB - The near-horizon metric for a black brane in anti-de Sitter space and the metric near the AdS boundary both exhibit hydrodynamic behavior. We demonstrate the equivalence of this pair of hydrodynamic systems for the sound mode of a conformal theory. This is first established for Einstein's gravity, but we then show how the sound damping constant will be modified from its Einstein form for a generalized theory. The modified damping constant is expressible as the ratio of a pair of gravitational couplings that are indicative of the sound-channel class of gravitons. This ratio of couplings differs from both that of the shear diffusion coefficient and the shear viscosity to entropy ratio. Our analysis is mostly limited to conformal theories, but suggestions are made as to how this restriction might eventually be lifted.

UR - http://www.scopus.com/inward/record.url?scp=67650841600&partnerID=8YFLogxK

U2 - 10.1103/PhysRevD.79.126012

DO - 10.1103/PhysRevD.79.126012

M3 - Article

AN - SCOPUS:67650841600

VL - 79

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

SN - 1550-7998

IS - 12

M1 - 126012

ER -