We present an efficient method for computing the zero frequency limit of
transport coefficients in strongly coupled field theories described
holographically by higher derivative gravity theories. Hydrodynamic
parameters such as shear viscosity and conductivity can be obtained by
computing residues of poles of the off-shell lagrangian density. We
clarify in which sense these coefficients can be thought of as effective
couplings at the horizon, and present analytic, Wald-like formulae for the
shear viscosity and conductivity in a large class of general higher
derivative lagrangians. We show how to apply our methods to systems at
zero temperature but finite chemical potential. Our results imply that such
theories satisfy \eta/s = 1/4\pi universally in the Einstein-Maxwell
sector. Likewise, the zero frequency limit of the real part of the
conductivity for such systems is shown to be universally zero, and we
conjecture that higher derivative corrections in this sector do not modify
this result to all orders in perturbation theory.
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