De Sitter Quantum Loops as the origin of Primordial Non-Gaussianities

TL;DR

This paper investigates how quantum loops involving a scalar field during inflation can generate significant primordial non-Gaussianities, analyzing their effects on curvature fluctuations and comparing with CMB constraints.

Contribution

It provides explicit calculations of three- and four-point correlations in a simple inflationary model focusing on small scalar mass effects.

Findings

Quantum loops can dominate primordial non-Gaussianities in certain inflation models.

Explicit expressions for bispectrum and trispectrum in specific limits are derived.

Model constraints are discussed based on CMB non-Gaussianity limits.

Abstract

It was pointed out recently that in some inflationary models quantum loops containing a scalar of mass $m$ that couples to the inflaton can be the dominant source of primordial non-Gaussianities. We explore this phenomenon in the simplest such model focusing on the behavior of the primordial curvature fluctuations for small $m/H$. Explicit calculations are done for the three and four point curvature fluctuation correlations. Constraints on the parameters of the model from the CMB limits on primordial non-Gaussianity are discussed. The bi-spectrum in the squeezed limit and the tri-spectrum in the compressed limit are examined. The form of the $n$-point correlations as any partial sum of wave vectors get small is determined.