Constraining Primordial Black Hole Formation from Single-Field Inflation

TL;DR

This paper investigates how single-field inflation models that produce primordial black holes can be constrained by large-scale cosmological observations, through analyzing one-loop corrections to the power spectrum.

Contribution

It introduces a calculation of one-loop corrections in models with sharp transitions in slow-roll parameters, linking small-scale black hole formation to large-scale observational constraints.

Findings

Models producing primordial black holes induce nonperturbative couplings on large scales.

Large-scale cosmological observations can constrain small-scale power spectra.

One-loop corrections reveal significant effects in models with sharp slow-roll transitions.

Abstract

The most widely studied formation mechanism of a primordial black hole is collapse of large-amplitude perturbation on small scales generated in single-field inflation. In this Letter, we calculate one-loop correction to the large-scale power spectrum in a model with sharp transition of the second slow-roll parameter. We find that models producing an appreciable amount of primordial black holes induce nonperturbative coupling on a large scale probed by cosmic microwave background radiation. Our result implies that a small-scale power spectrum can be constrained by large-scale cosmological observations.