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Abstract: Motivated by the vast string landscape, we consider the shear viscosity toentropy density ratio in conformal field theories dual to Einstein gravity withcurvature square corrections. After field redefinitions these theories reduceto Gauss-Bonnet gravity, which has special properties that allow us to computethe shear viscosity nonperturbatively in the Gauss-Bonnet coupling. By tuningof the coupling, the value of the shear viscosity to entropy density ratio canbe adjusted to any positive value from infinity down to zero, thus violatingthe conjectured viscosity bound. At linear order in the coupling, we also checkconsistency of four different methods to calculate the shear viscosity, and wefind that all of them agree. We search for possible pathologies associated withthis class of theories violating the viscosity bound.



Autor: Mauro Brigante, Hong Liu, Robert C. Myers, Stephen Shenker, Sho Yaida

Fuente: https://arxiv.org/







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