Primordial Black Holes from Multifield Inflation with Nonminimal Couplings

TL;DR

This paper explores multifield inflation models with nonminimal couplings that can produce primordial black holes in the right mass range to account for dark matter, aligning with current observational data.

Contribution

It introduces realistic high-energy physics inspired inflationary models with multiple fields and nonminimal couplings, capable of generating primordial black holes consistent with observations.

Findings

Models produce PBHs with masses suitable for dark matter.

Predictions align with recent measurements of spectral index and tensor-to-scalar ratio.

At least one parameter requires fine-tuning for PBH formation.

Abstract

Primordial black holes (PBHs) provide an exciting prospect for accounting for dark matter. In this paper, we consider inflationary models that incorporate realistic features from high-energy physics -- including multiple interacting scalar fields and nonminimal couplings to the spacetime Ricci scalar -- that could produce PBHs with masses in the range required to address the present-day dark matter abundance. Such models are consistent with supersymmetric constructions, and only incorporate operators in the effective action that would be expected from generic effective field theory considerations. The models feature potentials with smooth large-field plateaus together with small-field features that can induce a brief phase of ultra-slow-roll evolution. Inflationary dynamics within this family of models yield predictions for observables in close agreement with recent measurements, such as the spectral index of primordial curvature perturbations and the ratio of power spectra for tensor to scalar perturbations. As in previous studies of PBH formation resulting from a period of ultra-slow-roll inflation, we find that at least one dimensionless parameter must be highly fine-tuned to produce PBHs in the relevant mass-range for dark matter. Nonetheless, we find that the models described here yield accurate predictions for a significant number of observable quantities using a smaller number of relevant free parameters.