Perturbative evaluation of scalar two-point function in the cosmic microwave background power spectrum

Understand

Recent work in the literature has found a suppression or, instead, an enhancement of the Cosmic Microwave Background power spectrum in quantum gravity, although the effect is too small to be observed, in both cases.

• The present paper studies in detail the equations recently proposed for a Born-Oppenheimer-type analysis of the problem.
• By using a perturbative approach to the analysis of the nonlinear ordinary differential equation obeyed by the two-point function for scalar fluctuations, we find various explicit forms of such a two-point function, with the associated power spectrum.
• In particular, a new family of power spectra is obtained and studied.