Primordial Black Holes from String Inflation

TL;DR

This paper proposes a string inflation model that naturally produces primordial black holes in the low mass range, potentially explaining dark matter, by leveraging a tunable potential with a plateau and inflection point.

Contribution

It introduces a single-field string inflation model with a specific potential that enhances primordial black hole formation, grounded in string theory and stabilized by shift symmetry.

Findings

Primordial black holes can form in the model's low mass region.

The model's potential features a plateau and an inflection point.

Parameter tunability is achieved via the string landscape.

Abstract

We present a single-field string inflationary model which allows for the generation of primordial black holes in the low mass region where they can account for a significant fraction of the dark matter abundance. The potential is typical of type IIB fibre inflation models and features a plateau at CMB scales and a near inflection point at large distance scales where the power spectrum is enhanced due to a period of ultra slow-roll. The tunability of the underlying parameters is guaranteed by scanning through the string landscape and their stability against quantum corrections is ensured by an effective shift symmetry.