Non-Gaussianity as a Particle Detector

TL;DR

This paper explores how massive particles with spin during inflation can leave detectable non-Gaussian signatures in cosmological correlators, providing new templates for observational searches.

Contribution

It classifies couplings of massive spinning particles to inflationary fields within the effective field theory framework and derives explicit non-Gaussian shape functions.

Findings

Observable non-Gaussianity can arise for particles near the Hubble scale.

Explicit scalar and tensor bispectrum shapes are derived.

Breaking conformal symmetry enhances non-Gaussian signals.

Abstract

We study the imprints of massive particles with spin on cosmological correlators. Using the framework of the effective field theory of inflation, we classify the couplings of these particles to the Goldstone boson of broken time translations and the graviton. We show that it is possible to generate observable non-Gaussianity within the regime of validity of the effective theory, as long as the masses of the particles are close to the Hubble scale and their interactions break the approximate conformal symmetry of the inflationary background. We derive explicit shape functions for the scalar and tensor bispectra that can serve as templates for future observational searches.