The covariance of multi-field perturbations, pseudo-susy and f_NL

TL;DR

This paper develops a covariant formalism for multi-field cosmological perturbations, clarifies existing issues, and employs pseudo-supersymmetry to derive exact expressions relevant for understanding non-Gaussianity.

Contribution

It introduces a covariant approach to multi-field perturbations and applies pseudo-supersymmetry to obtain exact analytical results.

Findings

Clarifies the role of covariance in multi-field perturbation theory

Derives exact expressions for key perturbation terms using pseudo-susy

Provides insights into non-Gaussianity parameter f_NL

Abstract

We reconsider cosmological perturbation theory for multi-component scalars, enforcing covariance in field-space, and ensuring that phyical observations are independent of field re-definitions. We use the formalism to clarify some issues in the literature, and use pseudo-supersymmetry to derive exact expressions for terms of interest.