PBH formation in EFT of single field inflation with sharp transition

TL;DR

This paper explores PBH formation during a sharp transition in single field inflation within EFT, revealing causality violations due to one-loop corrections and the impact of non-canonical features on predictions.

Contribution

It demonstrates causality violation caused by one-loop corrections in PBH formation during sharp transitions in EFT of inflation and analyzes effects of non-canonical features.

Findings

Causality violation ($c_s>1$) for PBHs with mass > 10^2 g during transition.

Non-canonical features with $c_s<1$ worsen inflation predictions.

One-loop corrections significantly impact the power spectrum.

Abstract

Using the Effective Field Theory (EFT) framework of single field inflation, we investigate the possibility of the formation of Primordial Black Holes (PBHs) in the Slow Roll (SR) to Ultra Slow Roll (USR) sharp transition. We demonstrate that, due to one-loop correction to the power spectrum, causality is violated ($c_s>1$) for the mass range of PBHs, $M_{\rm PBH}>10^{2}{\rm gm}$ created during the said transition. We find that non-canonical features with $c_s<1$ worsen the predictions of the canonical framework of single-field inflation.