Primordial non-Gaussianities

TL;DR

This paper reviews the theoretical aspects of primordial non-Gaussianities, discussing formalism and various inflationary models, with a focus on potential signatures in isocurvature perturbations.

Contribution

It provides a comprehensive overview of the formalism and models related to primordial non-Gaussianities, highlighting the role of isocurvature perturbations.

Findings

Different classes of inflationary models produce distinct non-Gaussian signatures.

Isocurvature perturbations may leave unique imprints in non-Gaussianities.

The formalism aids in understanding nonlinear cosmological perturbations.

Abstract

This contribution gives an overview on primordial non-Gaussianities from a theoretical perspective. After presenting a general formalism to describe nonlinear cosmological perturbations, several classes of models, illustrated with examples, are discussed: multi-field inflation with non-standard Lagrangians, modulaton fields, curvaton fields. In the latter case, a special emphasis is put on the isocurvature perturbations, which could leave a specific signature in non-Gaussianities.