Is there a quantum gravity effect on the cosmic microwave background power spectrum?

TL;DR

This paper evaluates how quantum gravity might influence the cosmic microwave background's anisotropy spectrum, finding that potential effects are too small for current detection but exploring various theoretical schemes.

Contribution

It compares different quantum gravity approaches and their predicted effects on the CMB power spectrum, introducing new perturbative solutions and analyses.

Findings

Quantum gravity effects could enhance or suppress large-scale power.

Predicted effects are too small for current observational detection.

New power spectra families are derived from a Born-Oppenheimer analysis.

Abstract

An assessment is made of recent attempts to evaluate how quantum gravity may affect the anisotropy spectrum of the cosmic microwave background. A perturbative scheme for the solution of the Wheeler-DeWitt equation has been found to allow for enhancement of power at large scales, whereas the alternative predicts a suppression of power at large scales. Both effects are corrections which, although conceptually interesting, turn out to be too small to be detected. Another scheme relies upon a Born-Oppenheimer analysis: by using a perturbative approach to the nonlinear ordinary differential equation obeyed by the two-point function for scalar fluctuations, a new family of power spectra have been obtained and studied by the authors.