Dynamical Chaos and the Growth of Cosmological Fluctuations

I demonstrate that instability in a system of homogeneous scalar fields leads to the growth of super-Hubble metric perturbations. This generalizes the result that parametric resonance can lead to the growth of cosmological perturbations. Since dynamical chaos is common in multi-field quartically coupled systems, I argue that the evolution of the fields after inflation must be examined to determine whether the amplitude of cosmological metric perturbations is underestimated in the standard inflationary calculations. I illustrate this effect with a simple hybrid inflation model.