# Viscosity bound and causality in a superfluid plasma

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## Recording Details

Speaker(s):
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PIRSA Number:
10110054

## Abstract

In this talk I will discuss the applications of the gauge/gravity duality to the strongly coupled quark gluon plasma, focusing in particular on the role of the shear viscosity to entropy ratio.
It has been argued that the lower bound on the shear viscosity to entropy density in strongly coupled plasmas can be understood in terms of microcausality violation in the dual gravitational description.
However, since the transport properties of the system characterize its infrared dynamics, while the causality of the theory is determined by its ultraviolet behavior, the link between the viscosity bound and microcausality should not be applicable in theories that undergo low temperature phase transitions.
I will discuss an explicit holographic model confirming this fact, in which there is a decoupling'' of UV from IR physics.