Primordial scalar power spectrum from the Euclidean Big Bounce

TL;DR

This paper calculates the scalar power spectrum in a loop quantum cosmology model featuring a Euclidean phase, revealing IR suppression, oscillations, and UV rise, which could inform early universe understanding.

Contribution

It introduces a method to compute the scalar power spectrum across a Euclidean phase in loop quantum cosmology, highlighting novel spectral features.

Findings

Power spectrum shows IR suppression and oscillations.

Euclidean phase affects the evolution of scalar perturbations.

UV extension indicates a rise in power at high energies.

Abstract

In effective models of loop quantum cosmology, the holonomy corrections are associated with deformations of space-time symmetries. The most evident manifestation of the deformations is the emergence of an Euclidean phase accompanying the non-singular bouncing dynamics of the scale factor. In this article, we compute the power spectrum of scalar perturbations generated in this model, with a massive scalar field as the matter content. Instantaneous and adiabatic vacuum-type initial conditions for scalar perturbations are imposed in the contracting phase. The evolution through the Euclidean region is calculated based on the extrapolation of the time direction pointed by the vectors normal to the Cauchy hypersurface in the Lorentzian domains. The obtained power spectrum is characterized by a suppression in the IR regime and oscillations in the intermediate energy range. Furthermore, the speculative extension of the analysis in the UV reveals a specific rise of the power.