Resumming Cosmic Perturbations

Renormalization group (RG) techniques have been successfully employed in quantum field theory and statistical physics. Here we apply RG methods to study the non-linear stages of structure formation in the universe. Exact equations for the power spectrum, the bispectrum, and all higher order correlation functions can be derived for any underlying cosmological model. A remarkable feature of the RG flow is the emergence of an intrinsic UV cut-off, due to dark matter velocity dispersion, which improves the convergence of the equations at small scales. As a consequence, the method is able to follow the non-linear evolution of the power spectrum down to zero redshift and to length scales where perturbation theory fails. Our predictions accurately fit the results of N-body simulations in reproducing the 'baryon acoustic oscillation' features of the power spectrum, which will be accurately measured in future galaxy surveys and will provide a probe for distinguishing among different dark energy models.