Non-perturbative approach for curvature perturbations in stochastic-$\delta N$ formalism

摘要: In our previous paper, we have proposed a new algorithm to calculate the power spectrum of curvature perturbations generated in inflationary universe with use stochastic approach. Since this does not need perturbative expansion respect inflaton fields on super-horizon scale, it works even highly cases. For example, when are very large or non-Gaussianities sizable, may break down but enables perturbations. We apply two well-known inflation models, chaotic and hybrid inflation, paper. Especially for while potential is flat around critical point standard computation problematic, successfully