The Primordial Black Hole Formation from Single-Field Inflation is Not Ruled Out

TL;DR

This paper argues that primordial black hole formation via ultra-slow-roll single-field inflation remains plausible, as loop corrections do not significantly alter the large-scale power spectrum, thus not ruling out this scenario.

Contribution

It demonstrates that loop corrections are small in the ultra-slow-roll inflation scenario, supporting the viability of primordial black hole formation from this mechanism.

Findings

Loop corrections are negligible in the scenario.

The formation scenario is not ruled out by theoretical constraints.

Supports the plausibility of primordial black holes from single-field inflation.

Abstract

A standard scenario to form primordial black holes in the early universe is based on a phase of ultra-slow-roll in single-field inflation when the amplitude of the short scale modes is enhanced compared to the CMB plateau. Based on general arguments, we show that the loop corrections to the large-scale linear power spectrum from the short modes are small and conclude that the scenario is not ruled out.