Mode coupling on a geometrodynamical quantization of an inflationary universe

TL;DR

This paper investigates quantum-gravity effects on primordial perturbations during inflation, revealing that mode interactions and back-reaction significantly alter the power spectrum's scale dependence, challenging previous independent mode assumptions.

Contribution

It introduces a geometrodynamical quantization approach that includes all mode back-reactions, showing their comparable impact to self-interactions on the power spectrum.

Findings

Quantum-gravity effects modify the primordial power spectrum.

Back-reaction effects are as significant as self-interactions.

A characteristic scale-dependence is introduced by quantum-gravity effects.

Abstract

A geometrodynamical quantization of an inflationary universe is considered in order to estimate quantum-gravity effects for the primordial perturbations. Contrary to previous studies in the literature, the back-reaction produced by all the modes of the system is included in our computations. Even if at a classical level the assumption that every mode evolves independently provides a good estimate for the dynamics, our results explicitly show that this is not the case when considering quantum-gravity effects. More precisely, both the self-interaction, as well as the back-reaction from other modes, provide a correction of the same order of magnitude to the usual power spectrum as computed in the approximation of quantum field theory on classical backgrounds. In particular, these quantum-gravity effects introduce certain characteristic scale-dependence on the expression of the power spectrum.