Non-Gaussianity of quantum fields during inflation

TL;DR

This paper reviews how non-Gaussian features in cosmological perturbations emerge during inflation, focusing on the in-in formalism and bispectrum calculations in single-field models.

Contribution

It provides a comprehensive overview of non-Gaussianity origins and compares bispectrum shapes with local-type non-Gaussianity in inflationary cosmology.

Findings

Calculation of the bispectrum in single-field inflation models

Comparison of bispectrum shapes with local non-Gaussianity

Discussion of non-Gaussianity from super-horizon dynamics

Abstract

In this review, we discuss how non-Gaussianity of cosmological perturbations arises from inflation. After introducing the in-in formalism to calculate the $n$-point correlation function of quantum fields, we present the computation of the bispectrum of the curvature perturbation generated in general single field inflation models. The shapes of the bispectrum are compared with the local-type non-Gaussianity that arises from non-linear dynamics on super-horizon scales.