Cosmological perturbations in teleparallel Loop Quantum Cosmology

TL;DR

This paper develops a novel approach to cosmological perturbations in Loop Quantum Cosmology by combining teleparallel $F(T)$ gravity with holonomy corrections, resulting in a matter bounce scenario that produces a scale-invariant spectrum but requires modifications to match observations.

Contribution

It introduces a new method using teleparallel $F(T)$ gravity to analyze perturbations in LQC, blending bounce dynamics with non-singular equations for improved cosmological modeling.

Findings

Achieved a scale-invariant power spectrum of perturbations.

Found the tensor-to-scalar ratio to be around 1, inconsistent with observations.

Proposed a transition to a quasi de Sitter phase to enhance scalar perturbations.

Abstract

Cosmological perturbations in Loop Quantum Cosmology (LQC) are usually studied incorporating either holonomy corrections, where the Ashtekar connection is replaced by a suitable sinus function in order to have a well-defined quantum analogue, or inverse-volume corrections coming from the eigenvalues of the inverse-volume operator. In this paper we will develop an alternative approach to calculate cosmological perturbations in LQC based on the fact that, holonomy corrected LQC in the flat Friedmann-Lema\^itre-Robertson-Walker (FLRW) geometry could be also obtained as a particular case of teleparallel $F(T)$ gravity (teleparallel LQC). The main idea of our approach is to mix the simple bounce provided by holonomy corrections in LQC with the non-singular perturbation equations given by $F(T)$ gravity, in order to obtain a matter bounce scenario as a viable alternative to slow-roll inflation. In our study, we have obtained an scale invariant power spectrum of cosmological perturbations. However, the ratio of tensor to scalar perturbations is of order $1$, which does not agree with the current observations. For this reason, we suggest a model where a transition from the matter domination to a quasi de Sitter phase is produced in order to enhance the scalar power spectrum.