On the non-linear scale of cosmological perturbation theory

On the non-linear scale of cosmological perturbation theory

Cosmological perturbation theory is an analytical tool to determine the dark matter power spectrum from the primordial fluctuations. However, it fails to converge at late times due to non-linear effects. In this talk we discuss several approaches to resummation in cosmological perturbation theory. After a short introduction, standard perturbation theory (SPT), renormalized perturbation theory (RPT) and the eikonal approximation are reviewed. Finally, a generalization to RPT is presented that elucidates the relation between these schemes.