PBH formation in EFT of single field inflation with sharp transition

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 (cs>1) for the mass range of PBHs, MPBH>102gm created during the said transition. We find that non-canonical features with cs<1 worsen the predictions of the canonical framework of single-field inflation.