PBH Dark Matter from Ultra-Slow-Roll Inflation in Horndeski Gravity

This paper investigates the production of primordial black holes (PBHs) as a dark matter candidate within the framework of Horndeski gravity. It focuses on a specific scenario where the inflationary dynamics is controlled by a cubic Horndeski interaction, leading to an ultra-slow-roll phase. The key finding is that this mechanism can amplify the curvature power spectrum on small scales, potentially generating asteroid-mass PBHs that could account for a significant fraction of dark matter, while also predicting observable gravitational wave signatures. The work is significant because it provides a concrete mechanism for PBH formation within a well-motivated theoretical framework, addressing the dark matter problem and offering testable predictions.