Hybrid $\alpha$-attractors, primordial black holes and gravitational wave backgrounds

TL;DR

This paper explores hybrid $lpha$-attractor models of inflation, showing they can produce primordial black holes and gravitational wave backgrounds consistent with observations, due to their unique perturbation spectra.

Contribution

It introduces a two-stage inflation model within hybrid $lpha$-attractors that predicts observable primordial black holes and gravitational waves, expanding the understanding of early universe phenomena.

Findings

Inflationary perturbation spectrum aligns with Planck/BICEP/Keck data.

Model predicts high peaks at small scales leading to primordial black hole formation.

Generation of stochastic gravitational wave background from the model.

Abstract

We investigate the two-stage inflation regime in the theory of hybrid cosmological $\alpha$-attractors. The spectrum of inflationary perturbations is compatible with the latest Planck/BICEP/Keck results, thanks to the attractor properties of the model. However, at smaller scales, it may have a very high peak of controllable width and position, leading to a copious production of primordial black holes (PBH) and generation of a stochastic background of gravitational waves (SGWB).