Dynamical renormalization and universality in classical multifield cosmological models

We study the scaling behavior of classical multifield cosmological models with complete scalar manifold (M,G) and positive smooth scalar potential Φ, introducing a dynamical renormalization group action which relates their UV and IR limits. We show that the RG flow of such models interpolates between a modification of the geodesic flow of (M,G) (obtained in the UV limit) and the gradient flow of (M,G,V) (obtained in the IR limit), where the classical effective potential V is proportional to 2Φ. Using this fact, we show that two-field models whose scalar manifold has constant Gaussian curvature equal to −1, 0 or 1 are infrared universal in the sense that they suffice to describe the first order IR approximants of cosmological orbits for all two-field models with positive smooth scalar potential.