Shear viscosity in a non-Fermi-liquid phase of a quadratic semimetal

We study finite temperature transport in the Luttinger-Abrikosov-Beneslavskii phase-an interacting, scale invariant, non-Fermi-liquid phase found in quadratic semimetals. We develop a kinetic equation formalism to describe the dc transport properties, which are dominated by collisions, and compute the shear viscosity eta. The ratio of shear viscosity to entropy density eta/s is a measure of the strength of interaction between the excitations of a quantum fluid. As a consequence of the quantum critical nature of the system, eta/s is a universal number and we find it to be consistent with a bound proposed from gauge-gravity duality.