Chasing the non-linear evolution of matter power spectrum with numerical resummation method: solution of closure equations

We present a new numerical scheme to treat the non-linear evolution of cosmological power spectra. Governing equations for matter power spectra have been previously derived by a non-perturbative technique with closure approximation. Solutions of the resultant closure equations just correspond to the resummation of an infinite class of perturbation corrections, and they consistently reproduce the one-loop results of standard perturbation theory. We develop a numerical algorithm to solve closure evolutions in both perturbative and non-perturbative regimes. The present numerical scheme is particularly suited for examining non-linear matter power spectrum in general cosmological models, including modified theory of gravity. As a demonstration, we study weakly non-linear evolution of power spectrum in a class of modified gravity models, as well as various dark energy models.