Inflation with shallow dip and primordial black holes

TL;DR

This paper investigates a toy model of ultra slow-roll inflation with a shallow dip, showing how it enhances primordial perturbations and generates gravitational waves, potentially leading to primordial black holes and observable signals.

Contribution

It introduces a simplified ultra slow-roll inflation model with a shallow dip, analyzing its effects on the power spectrum and gravitational wave production.

Findings

Enhanced curvature perturbations in the model

Predicted gravitational wave signals within future detection scope

Estimated bounds on perturbation enhancement

Abstract

Primordial black holes may arise through ultra slow-roll inflation. In this work we study a toy model of ultra slow-roll inflation with a shallow dip. The ultra slow-roll stage enhances the curvature perturbations and thus the primordial scalar power spectrum. We analyze the features of the power spectrum numerically and analytically, and then give a rough estimate of the lower and upper bound of the enhancement. These large perturbations also produce second order gravitational waves, which are in the scope of future observations.