Abstract
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 language | English (US) |
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Article number | 066003 |
Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |
Volume | 80 |
Issue number | 6 |
DOIs | |
State | Published - Sep 3 2009 |
Externally published | Yes |
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)