Repository logo
 

Entropy production, viscosity bounds and bumpy black holes

Published version
Peer-reviewed

Type

Article

Change log

Authors

Hartnoll, SA 
Ramirez, DM 
Santos, JE 

Abstract

The ratio of shear viscosity to entropy density, η/s, is computed in various holographic geometries that break translation invariance (but are isotropic). The shear viscosity does not have a hydrodynamic interpretation in such backgrounds, but does quantify the rate of entropy production due to a strain. Fluctuations of the metric components δg xy are massive about these backgrounds, leading to η/s < 1/(4π) at all finite temperatures (even in Einstein gravity). As the temperature is taken to zero, different behaviors are possible. If translation symmetry breaking is irrelevant in the far IR, then η/s tends to a constant at T = 0. This constant can be parametrically small. If the translation symmetry is broken in the far IR (which nonetheless develops emergent scale invariance), then η/s ∼ T 2 ν as T → 0, with ν ≤ 1 in all cases we have considered. While these results violate simple bounds on η/s, we note that they are consistent with a possible bound on the rate of entropy production due to strain.

Description

Keywords

AdS-CFT correspondence, black holes, holography and condensed matter physics (AdS/CMT), holography and quark-gluon plasmas

Journal Title

Journal of High Energy Physics

Conference Name

Journal ISSN

1029-8479
1029-8479

Volume Title

2016

Publisher

Springer
Sponsorship
Science and Technology Facilities Council (ST/L000385/1)
Science and Technology Facilities Council (ST/L000636/1)
Science and Technology Facilities Council (ST/J005673/1)
Science and Technology Facilities Council (ST/K00333X/1)
Science and Technology Facilities Council (ST/M007065/1)