Non-perturbative unitarity constraints on the ratio of shear viscosity to entropy density in ultraviolet-complete theories with a gravity dual

Brustein, R; Medved, A J M

Title: Non-perturbative unitarity constraints on the ratio of shear viscosity to entropy density in ultraviolet-complete theories with a gravity dual
Creator: Brustein, R, Medved, A J M
Date: 2011
Type: text
Type: Article
Identifier: vital:6817
Identifier: http://hdl.handle.net/10962/d1004327
Description: We reconsider, from a novel perspective, how unitarity constrains the corrections to the ratio of shear viscosity η to entropy density s. We start with higher-derivative extensions of Einstein gravity in asymptotically anti-de Sitter spacetimes. It is assumed that these theories are derived from string theory and thus have a unitary UV completion that is dual to a unitary, UV-complete boundary gauge theory. We then propose that the gravitational perturbations about a solution of the UV-complete theory are described by an effective theory whose linearized equations of motion have at most two time derivatives. Our proposal leads to a concrete prescription for the calculation of η/s for theories of gravity with arbitrary higher-derivative corrections. The resulting ratio can take on values above or below 1/4π and is consistent with all the previous calculations, even though our reasoning is substantially different. For the purpose of calculating η/s, our proposal also leads to only two possible candidates for the effective two-derivative theory: Einstein and Gauss-Bonnet gravity. The distinction between the two is that Einstein gravity satisfies the equivalence principle, and so its graviton correlation functions are polarization-independent, whereas the Gauss-Bonnet theory has polarization-dependent correlation functions. We discuss the graviton three-point functions in this context and explain how these can provide additional information on the value of η/s.
Format: 41 pages, pdf
Language: English
Relation: Brustein, R and Medved, A.J.M (2011) Non-perturbative unitarity constraints on the ratio of shear viscosity to entropy density in ultraviolet-complete theories with a gravity dual. Physical Review D, 84 (12). p. 126001. Available: http://dx.doi.org/10.1103/PhysRevD.84.126005

Hits: 824
Visitors: 896
Downloads: 90

Collections

Medved, Joey (Prof)

RU Department of Physics and Electronics

SDG 09. Industry, Innovation and Infrastructure

		Thumbnail	File	Description	Size	Format
View Details			SOURCEPDF	PDF	268 KB	Adobe Acrobat PDF	View Details