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arXiv · 0802.3318

Viscosity Bound and Causality Violation

Mauro Brigante·Hong Liu·Robert C. Myers·Stephen Shenker·Sho Yaida
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Abstract

In recent work we showed that, for a class of conformal field theories (CFT) with Gauss-Bonnet gravity dual, the shear viscosity to entropy density ratio, $η/s$, could violate the conjectured Kovtun-Starinets-Son viscosity bound, $η/s\geq1/4π$. In this paper we argue, in the context of the same model, that tuning $η/s$ below $(16/25)(1/4π)$ induces microcausality violation in the CFT, rendering the theory inconsistent. This is a concrete example in which inconsistency of a theory and a lower bound on viscosity are correlated, supporting the idea of a possible universal lower bound on $η/s$ for all consistent theories.

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Mauro Brigante, Hong Liu, Robert C. Myers, Stephen Shenker, Sho Yaida. 2008-05-22. Viscosity Bound and Causality Violation. https://doi.org/10.1103/physrevlett.100.191601

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