Superbounce and Loop Quantum Ekpyrotic Cosmologies from Modified Gravity: $F(R)$, $F(G)$ and $F(T)$ Theories

TL;DR

This paper explores how modified gravity theories like $F(R)$, $F(G)$, and $F(T)$ can produce bouncing cosmologies such as superbounce and loop quantum ekpyrosis, analyzing their stability and universality.

Contribution

It reconstructs specific subclasses of modified gravity theories that realize bouncing cosmologies and analyzes their stability, highlighting potential universality in such models.

Findings

Reconstructed $F(R)$, $F(G)$, and $F(T)$ models for bounce scenarios.

Identified stability conditions for these bouncing solutions.

Indicated possible universality among different effective gravities.

Abstract

We investigate the realization of two bouncing paradigms, namely of the superbounce and the loop quantum cosmological ekpyrosis, in the framework of various modified gravities. In particular, we focus on the $F(R)$, $F(G)$ and $F(T)$ gravities, and we reconstruct their specific subclasses which lead to such universe evolutions. These subclasses constitute from power laws, polynomials, or hypergeometric ansatzes, which can be approximated by power laws. The qualitative similarity of different effective gravities which realize the above two bouncing cosmologies, indicates to some universality lying behind such a bounce. Finally, performing a linear perturbation analysis, we show that the obtained solutions are conditionally or fully stable.