Natural Covariant Planck Scale Cutoffs and the Cosmic Microwave Background Spectrum

TL;DR

This paper investigates how covariant quantum gravity-inspired ultraviolet cutoffs during inflation could produce observable oscillations in the cosmic microwave background spectrum, potentially detectable with future measurements.

Contribution

It introduces a fully covariant modeling of ultraviolet cutoffs in inflation, predicting specific oscillatory features in the CMB spectrum.

Findings

Oscillations in the spectrum depend linearly on the ratio of Planck to Hubble lengths.

The effect size could be as large as one part in 10^5, making it potentially observable.

Covariant cutoffs produce characteristic $k$-dependent oscillations in the spectrum.

Abstract

We calculate the impact of quantum gravity-motivated ultraviolet cutoffs on inflationary predictions for the cosmic microwave background spectrum. We model the ultraviolet cutoffs fully covariantly to avoid possible artifacts of covariance breaking. Imposing these covariant cutoffs results in the production of small, characteristically $k-$dependent oscillations in the spectrum. The size of the effect scales linearly with the ratio of the Planck to Hubble lengths during inflation. Consequently, the relative size of the effect could be as large as one part in $10^5$; i.e., eventual observability may not be ruled out.