Role of the counterterms in the conservation of superhorizon curvature perturbations at one loop

TL;DR

This paper demonstrates that counterterms are essential in canceling one-loop corrections to superhorizon curvature perturbations in single-field inflation, ensuring their conservation, contrary to recent claims.

Contribution

It clarifies the role of counterterms in preserving superhorizon curvature perturbation conservation at one loop in inflation models.

Findings

Counterterms cancel the one-loop power spectrum contributions.

Superhorizon curvature perturbations remain conserved at one loop.

Counterterm contributions were previously overlooked.

Abstract

Recently, several papers have claimed that superhorizon curvature perturbations are not conserved at the one-loop level in single-field inflation models if there is a transient ultra-slow-roll period. In this work, we point out that the contributions from the counterterms were overlooked in the recent papers. We show that the counterterm contributions play a crucial role in canceling the one-loop power spectrum of superhorizon curvature perturbations in the comoving gauge.