# Primordial black holes from sound speed resonance in the inflaton-curvaton mixed scenario

## TL;DR

This paper explores how sound speed resonance during inflation in a mixed inflaton-curvaton model can generate enhanced small-scale density perturbations, leading to primordial black holes that could account for dark matter.

## Contribution

It introduces a novel mechanism of sound speed resonance in a mixed inflaton-curvaton scenario for primordial black hole formation, highlighting its potential to produce dark matter.

## Key findings

- Enhanced small-scale density perturbations due to SSR
- Primordial black holes with specific mass spectrum can form
- PBHs can constitute dark matter in this scenario

## Abstract

We study sound speed resonance (SSR) mechanism for primordial black hole (PBH) formation in an early universe scenario with inflaton and curvaton being mixed. In this scenario, the total primordial density perturbations can be contributed by the fluctuations from both the inflaton and curvaton fields, in which the inflaton fluctuations lead to the standard adiabatic perturbations, while the sound speed of the curvaton fluctuations are assumed to be oscillating during inflation. Due to the narrow resonance effect of SSR mechanism, we acquire the enhanced primordial density perturbations on small scales and it remains nearly scale-invariant on large scales, which is essential for PBH formation. Finally, we find that the PBHs with specific mass spectrum can be produced with a sufficient abundance for dark matter in the mixed scenario.