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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 cutoff, 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 Oscillations'' features of the power-spectrum, which will be accurately measured in future galaxy surveys and will provide a probe to distinguish among different dark energy models.