Primordial black holes and scalar induced gravitational waves from Higgs inflation with non-canonical kinetic term

TL;DR

This paper investigates Higgs inflation with a non-canonical kinetic term, showing it can produce primordial black holes and scalar induced gravitational waves consistent with observations, and explores non-Gaussian effects on these phenomena.

Contribution

It introduces a nonminimal coupling in Higgs inflation to resolve potential restrictions and analyzes the impact of non-canonical kinetic coupling and non-Gaussianity on PBH and SIGW formation.

Findings

Higgs inflation with nonminimal coupling satisfies CMB constraints

Enhanced small-scale curvature perturbations lead to PBHs and SIGWs

Non-Gaussianity increases PBH formation without significantly affecting SIGWs

Abstract

We resolve the potential-restriction problem in K/G inflation by introducing nonminimal coupling. In this context, Higgs field successfully drives inflation satisfying CMB observations while enhancing curvature perturbations at small scales, which in turn accounts for primordial black holes (PBHs) and scalar induced gravitational waves (SIGWs). We then uncover the effect of the non-canonical kinetic coupling function in more detail and study its the observational constraint. Besides, we also give the gauge invariant expression for the integral kernel of SIGWs, which is related to terms propagating with the speed of light. Finally, the non-Gaussian effect on PBH abundance and SIGWs is studied. We find that non-Gaussianity makes PBHs form more easily, but its effect on the energy density of SIGWs is negligible.