Inflation from Multiple Pseudo-Scalar Fields: PBH Dark Matter and Gravitational Waves

TL;DR

This paper explores a multi-field inflation model with pseudo-scalars and gauge fields, producing primordial black holes and gravitational waves, potentially explaining dark matter and detectable by future observatories.

Contribution

It introduces a multi-stage inflation model with multiple peaks in curvature perturbations, linking PBH dark matter production and gravitational wave signals.

Findings

Multiple peaks in curvature spectrum during inflation.

Primordial black holes can account for significant dark matter.

Generated gravitational waves are within reach of upcoming detectors.

Abstract

We study a model of inflation with multiple pseudo-scalar fields coupled to a $U(1)$ gauge field through Chern-Simons interactions. Because of parity violating interactions, one polarization of the gauge field is amplified yielding to enhanced curvature perturbation power spectrum. Inflation proceeds in multiple stages as each pseudo-scalar field rolls towards its minimum yielding to distinct multiple peaks in the curvature perturbations power spectrum at various scales during inflation. The localized peaks in power spectrum generate Primordial Black Holes (PBHs) which can furnish a large fraction of Dark Matter (DM) abundance. In addition, gravitational waves (GWs) with non-trivial spectra are generated which are in sensitivity range of various forthcoming GW observatories.