Testing quantum gravity effects with latest CMB observations

TL;DR

This paper investigates how quantum gravity effects, modeled via non-commutative phase space, modify the primordial tensor power spectrum, and finds that these modifications better fit recent CMB observations, potentially resolving existing data tensions.

Contribution

It introduces a quantum gravity-inspired modification to the primordial tensor spectrum and demonstrates improved fit to CMB data over the standard model.

Findings

Modified power spectrum shows suppression on large scales.

Quantum gravity effects are statistically preferred at over 3σ.

Potential resolution of BICEP2 and Planck data tension.

Abstract

Inspired by quantum gravitational physics, the approach of non-commutative (NC) phase space leads to a modified dispersion relation of gravitational waves. This feature, if applied to the very early universe, gives rise to a modified power spectrum of primordial tensor perturbations with a suppression of power on large scales. We confront this phenomenon with the BICEP2 and Planck experiments, and show that inflation with the modified dispersion relation can simultaneously fit the observations better than the standard inflationary paradigm. In particular, the numerical result implies that with the latest cosmological microwave background (CMB) observations, a quantum gravity modified power spectrum of primordial tensor modes is preferred at a statistical significance of more than $3\sigma$ compared with the minimal model. Our study indicates that the potential tension between the BICEP2 and Planck data may be resolved by quantum gravity effects.