# PBH dark matter from axion inflation

## TL;DR

This paper explores how axion inflation models with non-minimal gravity coupling can naturally produce broad PBH mass spectra, potentially explaining all dark matter through PBHs.

## Contribution

It demonstrates that non-minimally coupled axion inflation models can generate broad PBH spectra, unlike minimally coupled models, with some parameters allowing PBHs to account for all dark matter.

## Key findings

- Broad PBH mass spectra naturally arise in non-minimal axion inflation.
- Specific parameters can produce PBHs that constitute all dark matter.
- Contrasts with minimally coupled models predicting scale-invariant PBH distributions.

## Abstract

Protected by an approximate shift symmetry, axions are well motivated candidates for driving cosmic inflation. Their generic coupling to the Chern-Simons term of any gauge theory gives rise to a wide range of potentially observable signatures, including equilateral non-Gaussianites in the CMB, chiral gravitational waves in the range of direct gravitational wave detectors and primordial black holes (PBHs). In this paper we revisit these predictions for axion inflation models non-minimally coupled to gravity. Contrary to the case of minimally coupled models which typically predict scale-invariant mass distributions for the generated PBHs at small scales, we demonstrate how broadly peaked PBH spectra naturally arises in this setup. For specific parameter values, all of dark matter can be accounted for by PBHs.