The Chern-Simons diffusion rate from higher curvature gravity

Understand

An important transport coefficient in the study of non-Abelian plasmas is the Chern-Simons diffusion rate, which parameterizes the rate of transition among the degenerate vacua of a gauge theory.

• We compute this quantity at strong coupling, via holography, using two theories of gravity with higher curvature corrections, namely Gauss-Bonnet gravity and quasi-topological gravity.
• We find that these corrections may either increase or decrease the result obtained from Einstein's gravity, depending on the value of the couplings.
• The Chern-Simons diffusion rate for Gauss-Bonnet gravity decreases as the shear viscosity over entropy ratio is increased.