Sound damping constant for generalized theories of gravity

Ram Brustein, A. J.M. Medved

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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.

Original languageEnglish
Article number126012
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number12
StatePublished - 19 Jun 2009

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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