Chern-Simons diffusion rate in a holographic Yang-Mills theory

Understand

Using holography, we compute the Chern-Simons diffusion rate of 4d gauge theories constructed by wrapping D4-branes on a circle.

• In the model with antiperiodic boundary conditions for fermions, we find that it scales like $T^6$ in the high-temperature phase.
• With periodic fermions, this scaling persists at low temperatures.
• The scaling is reminiscent of 6d hydrodynamic behavior even at temperatures small compared to compactification scales of the M5-branes from which the D4-branes descend.