Viscosity bound for anisotropic superfluids in higher derivative gravity

TL;DR

This paper analytically investigates how higher derivative gravity theories, specifically Einstein Gauss-Bonnet gravity, affect the shear viscosity to entropy ratio in superfluid phases, revealing non-universality and temperature-dependent corrections.

Contribution

It provides the first analytical computation of shear viscosity corrections in anisotropic superfluids within higher derivative gravity frameworks, highlighting non-universality and bounds modifications.

Findings

Finite temperature correction to viscosity ratio below critical temperature.

Upper bound on Gauss-Bonnet coupling remains stable near critical point.

Lower bound of viscosity ratio is modified by temperature effects.

Abstract

In the present paper, based on the principles of gauge/gravity duality we analytically compute the shear viscosity to entropy ratio corresponding to the superfluid phase in Einstein Gauss-Bonnet gravity. From our analysis we note that the ratio indeed receives a finite temperature correction below certain critical temperature. This proves the non universality of shear viscosity to entropy ratio in higher derivative theories of gravity. We also compute the upper bound for the Gauss-Bonnet coupling corresponding to the symmetry broken phase and note that the upper bound on the coupling does not seem to change as long as we are close to the critical point of the phase diagram. However the corresponding lower bound of the shear viscosity to entropy ratio seems to get modified due to the finite temperature effects.