Non-Equilibrium Dynamics in QCD and Holography: A Review

This paper reviews the application of hydrodynamic and holographic approaches to understand the non-equilibrium dynamics of the quark-gluon plasma created in heavy ion collisions. It highlights the challenges of describing these dynamics directly within QCD and the utility of effective theories and holographic models, particularly at strong coupling. The paper focuses on three specific examples: non-equilibrium shear viscosity, sound wave propagation, and the chiral magnetic effect, providing a valuable overview of current research in this area.