January 9: “Holographic effective actions for charged fluids” by Julio Virrueta

Abstract: I will discuss the real-time dynamics of gravitons and photon fluctuations around the AdS-Reissner-Nordstrom black hole and argue that the dynamics of these modes are captured by a set of designer scalars in the background geometry. I will show how it is possible to isolate the phonon mode, momentum, and charge diffusion modes, and identify the combination of currents that corresponds to each of them. Using these results I will obtain the real-time Gaussian effective action, which includes both the retarded response and the associated stochastic. Finally, I will discuss extensions beyond linear response.