Primordial power spectra for scalar perturbations in loop quantum cosmology

TL;DR

This paper computes the scalar perturbation power spectrum in loop quantum cosmology, proposing an initial vacuum state that aligns well with Planck observations and shows suppression of large-scale anisotropies.

Contribution

It introduces a new initial vacuum state for scalar perturbations in loop quantum cosmology and compares it with existing approaches, matching observational data.

Findings

Hybrid quantization aligns with dressed metric predictions.

Proposed vacuum state shows suppression of large-scale power.

Results are consistent with Planck mission observations.

Abstract

We provide the power spectrum of small scalar perturbations propagating in an inflationary scenario within loop quantum cosmology. We consider the hybrid quantization approach applied to a Friedmann--Robertson--Walker spacetime with flat spatial sections coupled to a massive scalar field. We study the quantum dynamics of scalar perturbations on an effective background within this hybrid approach. We consider in our study adiabatic states of different orders. For them, we find that the hybrid quantization is in good agreement with the predictions of the dressed metric approach. We also propose an initial vacuum state for the perturbations, and compute the primordial and the anisotropy power spectrum in order to qualitatively compare with the current observations of Planck mission. We find that our vacuum state is in good agreement with them, showing a suppression of the power spectrum for large scale anisotropies. We compare with other choices already studied in the literature.