One-loop corrections to the power spectrum in general single-field inflation

TL;DR

This paper calculates one-loop quantum corrections to the inflationary power spectrum in single-field models with small sound speed, providing bounds on model parameters to ensure perturbative validity.

Contribution

It offers a detailed computation of loop corrections for non-canonical single-field inflation, highlighting the impact of small sound speed on quantum effects.

Findings

Loop corrections are inversely proportional to powers of sound speed c_s.

Theoretical bounds on c_s are derived to maintain perturbation theory validity.

Large non-Gaussianities are associated with small sound speed models.

Abstract

We perform a thorough computation of the one-loop corrections from both scalar and tensor degrees of freedom to the power spectrum of curvature fluctuations for non-canonical Lagrangians in single-field inflation. We consider models characterized by a small sound speed c_{s}, which produce large non-Gaussianities. As expected, the corrections turn out to be inversely proportional to powers of c_{s}; evaluating their amplitudes it is then possible to derive some theoretical bounds on the sound speed by requesting the conditions necessary for perturbation theory to hold.