Bound on the speed of sound from holography

Aleksey Cherman, Thomas D. Cohen, Abhinav Nellore

Research output: Contribution to journalArticlepeer-review

68 Scopus citations


We show that the squared speed of sound vs2 is bounded from above at high temperatures by the conformal value of 1/3 in a class of strongly coupled four-dimensional field theories, given some mild technical assumptions. This class consists of field theories that have gravity duals sourced by a single-scalar field. There are no known examples to date of field theories with gravity duals for which vs2 exceeds 1/3 in energetically favored configurations. We conjecture that vs2=1/3 represents an upper bound for a broad class of four-dimensional theories.

Original languageEnglish (US)
Article number066003
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number6
StatePublished - Sep 3 2009
Externally publishedYes

ASJC Scopus subject areas

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


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