The Effect of Curvaton Decay on the Primordial Power Spectrum

TL;DR

This paper investigates how the decay of the curvaton field influences the primordial power spectrum, revealing an enhancement post-decay that does not lead to overproduction of primordial black holes.

Contribution

It provides analytical and numerical analysis of the curvaton decay impact on the primordial power spectrum, highlighting the controlled amplitude of curvature perturbations.

Findings

Power spectrum is enhanced after curvaton decay during radiation era.

Amplitude of Bardeen potential depends on curvaton energy fraction.

Enhancement is insufficient for primordial black hole overproduction.

Abstract

We study the effect of curvaton decay on the primordial power spectrum. Using analytical approximations and also numerical calculations, we find that the power spectrum is enhanced during the radiation dominated era after the curvaton decay. The amplitude of the Bardeen potential is controlled by the fraction of the energy density in the curvaton at the time of curvaton decay. We show that the enhancement in the amplitude of the primordial curvature perturbation is, however, not large enough to lead to primordial black hole overproduction on scales which re-enter the horizon after the time of curvaton decay.