Dynamic critical behavior of the chiral phase transition from the real-time functional renormalization group

Abstract: In the chiral limit the complicated many-body dynamics around the second-order chiral phase transition of two-flavor QCD can be understood by appealing to universality. We present a novel formulation of the real-time functional renormalization group that describes the stochastic hydrodynamic equations of motion for systems in the same dynamic universality class, which corresponds to Model G in the Halperin-Hohenberg classification. Our approach preserves all relevant symmetries of such systems with reversible mode couplings. We show that the calculations indeed produce the non-trivial value $z=d/2$ for the dynamic critical exponent, where $d$ is the number of spatial dimensions. From the momentum and temperature dependence of the diffusion coefficient of the conserved charge densities, we extract the dimensionless universal scaling function.