# Non-Canonical Inflation and Primordial Black Holes Production

## TL;DR

This paper explores how non-canonical inflation models with variable sound speed can significantly amplify scalar perturbations, potentially leading to primordial black hole formation that could account for dark matter.

## Contribution

It introduces a mechanism where non-standard kinetic terms in inflation cause perturbation amplification and PBH production, a novel approach in inflationary cosmology.

## Key findings

- Amplification of scalar spectrum due to decreasing sound speed.
- Formation of primordial black holes with masses around 10^{-15} solar masses.
- Potential explanation for dark matter as primordial black holes.

## Abstract

We study a mechanism for the amplification of the inflationary scalar perturbation when the inflaton field action is non-canonical, i.e. the inflaton kinetic term has a non-standard form. For such a case the speed of sound of the perturbations generated during inflation is less than one and in general changes with time. Furthermore in such models, even when the scalar field potential is negligible, diverse inflationary attractors may exist. The possible effects of a speed of sound approaching zero during some stage of inflation may lead to a large amplification for the amplitude of the scalar spectrum which, on horizon re-entry during the radiation dominated phase, can collapse and form primordial black holes (PBH) of a mass $M_{\rm BH}\sim 10^{-15}M_{\odot}$ which may constitute a large fraction of the total Dark Matter (DM) today.