Speaker
Paul Romatschke
(FIAS Frankfurt)
Description
Hydrodynamics predicts long-lived sound and shear waves.
Thermal fluctuations in these waves can lead to the diffusion of
momentum density, contributing to the shear viscosity and other
transport coefficients. Within viscous hydrodynamics in 3+1
dimensions, this leads to a positive contribution to the shear
viscosity, which is finite but inversely proportional to the
microscopic shear viscosity. Therefore the effective infrared
viscosity is bounded from below. The contribution to the second-order
transport coefficient $\tau_\pi$ is divergent, which means that
second-order relativistic viscous hydrodynamics is inconsistent below
some frequency scale. We estimate the importance of each effect for
the Quark-Gluon Plasma, finding them to be minor if $\eta/s = 0.16$
but important if $\eta/s = 0.08$.
Primary author
Paul Romatschke
(FIAS Frankfurt)
