Local Features with Large Spiky non-Gaussianities during Inflation

TL;DR

This paper introduces a mechanism during inflation where a sharp waterfall phase transition causes localized, large non-Gaussian features in curvature perturbations, impacting CMB anisotropies.

Contribution

It proposes a dynamical model linking waterfall phase transitions to localized non-Gaussian features in inflationary perturbations, a novel approach in inflation theory.

Findings

Sharp peak in curvature perturbation from waterfall quantum fluctuations

Large spike non-Gaussianity at specific modes

Potential observable effects on CMB anisotropies

Abstract

We provide a dynamical mechanism to generate localized features during inflation. The local feature is due to a sharp waterfall phase transition which is coupled to the inflaton field. The key effect is the contributions of waterfall quantum fluctuations which induce a sharp peak on the curvature perturbation which can be as large as the background curvature perturbation from inflaton field. Due to non-Gaussian nature of waterfall quantum fluctuations a large spike non-Gaussianity is produced which is narrowly peaked at modes which leave the Hubble radius at the time of phase transition. The large localized peaks in power spectrum and bispectrum can have interesting consequences on CMB anisotropies.