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

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 0 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 Veff(0) 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 Veff(0). In particular, models with bump and intermediate types give rise to primordial scalar and tensor power spectra consistent with the recent Planck data on scales relevant to the observations of the cosmic microwave background. This property is attributed to the fact that the number of e-foldings Delta N, acquired around the bump region of Veff(0) can be as small as a few, in contrast to the plateau type, where Delta N, typically exceeds the order of 10.

Automated summary

Primordial black holes (PBHs) can potentially account for all or part of the dark matter in the universe. Inflation provides a mechanism for generating the seeds of PBHs when the velocity of an inflaton field rapidly decreases. By studying the curvature perturbations during Gauss-Bonnet corrected Higgs inflation, we find that certain parameter spaces allow for the formation of PBHs that can contribute to all dark matter. In addition, we show that models with certain types of potential exhibit power spectra consistent with observational data.