Infrared Logarithms in Minisuperspace Inflation

TL;DR

This paper investigates infrared logarithms in minisuperspace inflation, showing that while perturbation theory predicts growing logarithmic corrections, a nonperturbative approach reveals a more stable behavior of the curvature perturbation.

Contribution

It provides a nonperturbative analysis of infrared logarithms in minisuperspace inflation, clarifying their true behavior beyond perturbative predictions.

Findings

Perturbation theory predicts $( abla a_B)^n$ corrections to $ abla \

Nonperturbative estimates show $ abla \

Curvature perturbation $ abla \

Abstract

We examine the emergence of the infrared logarithms in the cosmological perturbation theory applied to the minisuperspace scalar slow-roll inflation. Not surprisingly, in the single scalar field model the curvature perturbation $\zeta$ is conserved and no $\ln a_B$ behavior appears, where $a_B(t)$ is the background scale factor of the universe. On the other hand, in the presence of a spectator scalar the $n$'th order perturbation theory gives an $(\ln a_B)^n$ correction to $\zeta$. However, a nonperturbative estimate shows that $\zeta$ actually becomes the sum of a constant and a mildly evolving $\ln a_B$ pieces.