Primordial black holes from Higgs inflation with a Gauss-Bonnet coupling

TL;DR

This paper explores how Gauss-Bonnet corrected Higgs inflation can generate primordial black holes that account for dark matter, with specific potential structures producing observable power spectra consistent with Planck data.

Contribution

It introduces a novel inflation model with Gauss-Bonnet coupling that enhances curvature perturbations, leading to PBH formation and compatibility with CMB observations.

Findings

PBHs can constitute all dark matter in certain parameter spaces.

Bump- and intermediate-type potentials produce consistent power spectra with Planck data.

Effective potential structures influence the number of e-foldings and PBH formation.

Abstract

Primordial black holes (PBHs) can be the source for all or a part of today's dark matter density. Inflation provides a mechanism for generating the seeds of PBHs in the presence of a temporal period where the velocity of an inflaton field $\phi$ rapidly decreases toward 0. We compute the primordial power spectra of curvature perturbations generated during Gauss-Bonnet (GB) corrected Higgs inflation in which the inflaton field has not only a nonminimal coupling to gravity but also a GB coupling. For a scalar-GB coupling exhibiting a rapid change during inflation, we show that curvature perturbations are sufficiently enhanced by the appearance of an effective potential $V_{\rm eff}(\phi)$ containing the structures of plateau-type, bump-type, and their intermediate type. We find that there are parameter spaces in which PBHs can constitute all dark matter for these three types of $V_{\rm eff}(\phi)$. In particular, models with bump- and intermediate-types give rise to the primordial scalar and tensor power spectra consistent with the recent Planck data on scales relevant to the observations of cosmic microwave background. This property is attributed to the fact that the number of e-foldings $\Delta N_c$ acquired around the bump region of $V_{\rm eff}(\phi)$ can be as small as a few, in contrast to the plateau-type where $\Delta N_c$ typically exceeds the order of 10.