Issues Concerning Loop Corrections to the Primordial Power Spectra

TL;DR

This paper discusses the challenges and issues related to infrared loop corrections in the primordial power spectra from inflation, highlighting divergences and proposing a more well-behaved extension.

Contribution

It clarifies ten principles regarding infrared loop corrections and introduces an improved extension for scalar fluctuations that mitigates divergence issues.

Findings

Existing proposals introduce unrenormalizable ultraviolet divergences.

Loop corrections are enhanced by inverse powers of the slow roll parameter.

A new extension is proposed to improve the behavior of scalar fluctuation calculations.

Abstract

We expound ten principles in an attempt to clarify the debate over infrared loop corrections to the primordial scalar and tensor power spectra from inflation. Among other things we note that existing proposals for nonlinear extensions of the scalar fluctuation field $\zeta$ introduce new ultraviolet divergences which no one understands how to renormalize. Loop corrections and higher correlators of these putative observables would also be enhanced by inverse powers of the slow roll parameter $\epsilon$. We propose an extension which should be better behaved.