Inflation and Birth of Cosmological Perturbations

TL;DR

This paper reviews recent advances in inflationary cosmology, focusing on the generation of perturbations, non-Gaussianities, and the delta N formalism for nonlinear analysis.

Contribution

It provides a comprehensive overview of inflation models, perturbation types, and introduces the delta N formalism for nonlinear super Hubble scale analysis.

Findings

Summary of single-field slow-roll inflation and perturbations

Discussion of nonlinear, non-Gaussian perturbations in various models

Explanation of the delta N formalism for curvature perturbations

Abstract

We review recent developments in the theory of inflation and cosmological perturbations produced from inflation. After a brief introduction of the standard, single-field slow-roll inflation, and the curvature and tensor perturbations produced from it, we discuss possible sources of nonlinear, non-Gaussian perturbations in other models of inflation. Then we describe the so-called $\delta N$ formalism, which is a powerful tool for evaluating nonlinear curvature perturbations on super Hubble scales.