Higher order contributions to the primordial non-gaussianity

TL;DR

The paper addresses primordial non-Gaussianity by computing higher-order contributions to f_NL arising from the three-point function of field perturbations using the δN formalism. It derives two next-to-leading-order diagrams, evaluates their momentum dependence, and applies the results to single-field, multi-field chaotic, two-component, and curvaton scenarios. In all considered models, these higher-order corrections are found to be well below detectability, reinforcing the dominance of leading-order non-Gaussian signals. The findings help clarify the expected magnitude of non-Gaussianity in common inflationary frameworks and set expectations for interpreting future observational bounds.

Abstract

In this paper we calculate additional contributions to that part of the non-Gaussianity of the curvature perturbation, which come from the three-point correlator of the field perturbations. We estimate this contribution in the following models for its origin: single-component inflation, multi-component chaotic inflation, a two-component "hybrid" inflationary model, and the curvaton scenario. In all of these models, the additional contributions to the primordial non-gaussianity considered here, are too small to be ever detected.

Figures (1)

• Figure 1: Here we show the two possible diagrams. There are three external lines corresponding to the three momenta $k_1$, $k_2$ and $k_3$. The parallel lines represent the two-point correlator, whereas the crossed circle indicates the three-point correlator. The diagrams have been drawn using JaxoDraw Binosi:2003yf.