Equilateral non-Gaussianity from heavy fields

TL;DR

This paper investigates how self-interactions of heavy scalar fields during inflation influence primordial non-Gaussianity, deriving an effective theory and confirming results through two different computational methods.

Contribution

It introduces a detailed effective theory for heavy field self-interactions during inflation and demonstrates their impact on equilateral non-Gaussianity, verified by two calculation approaches.

Findings

Heavy fields can produce significant equilateral non-Gaussianity.

Effective theory aligns with in-in formalism results.

Self-interactions of heavy fields are relevant for inflationary predictions.

Abstract

The effect of self-interactions of heavy scalar fields during inflation on the primordial non-Gaussianity is studied. We take a specific constant-turn quasi-single field inflation as an example. We derive an effective theory with emphasis on non-linear self-interactions of heavy fields and calculate the corresponding non-Gaussianity, which is of equilateral type and can be as relevant as those computed previously in the literature. We also derive the non-Gaussianity by directly using the in-in formalism, and verify the equivalence of these two approaches.