We study time-dependent perturbations to a family of five-dimensional black
hole spacetimes constructed as a holographic model of the QCD phase diagram. We
use the results to calculate two transport coefficients, the bulk viscosity and
conductivity, as well as the associated baryon diffusion constant, throughout
the phase diagram. Near the critical point in the T-mu plane, the transport
coefficients remain finite, although their derivatives diverge, and the
diffusion goes to zero. This provides further evidence that large-N_c gauge
theories suppress convective transport. We also find a divergence in the
low-temperature bulk viscosity, outside the region expected to match QCD, and
compare the results to the transport behavior of known R-charged black holes.Comment: 40 pages, 11 figures, LaTe
