Slow-Roll Inflation at N3LO

TL;DR

This paper derives the scalar and tensor power spectra at N3LO for single-field slow-roll inflation, enabling precise analysis of small deviations in primordial spectra crucial for upcoming cosmological observations.

Contribution

It provides the first comprehensive N3LO slow-roll power spectra for all single-field inflation models, including those with varying sound speeds, addressing higher-order uncertainties.

Findings

Derived N3LO power spectra for scalar and tensor perturbations.

Encompasses models with varying sound speed, including string-inspired scenarios.

Facilitates robust parameter inference for future cosmological data.

Abstract

The next generation of cosmological observations will be sensitive to small deviations from a pure power law in the primordial power spectrum of the curvature perturbations. In the context of slow-roll inflation, these deviations are expected and correspond to the so-called running of the spectral index. Their measurement would bring as much information as the discovery of deviations from scale invariance. However, robust parameter inference requires to marginalize over any possible higher order uncertainties, which have been, up to now, not fully determined. We tackle this issue by deriving the inflationary scalar and tensor slow-roll power spectra at next-to-next-to-next to leading order (N3LO), fully expanded around an observable pivot wavenumber, for all single field inflationary models having minimal and non-minimal kinetic terms. Our result therefore encompasses string-inspired inflationary models having a varying speed of sound.