Stable bouncing solutions in Teleparallel Horndeski gravity: violations of the no-go theorem

TL;DR

This paper demonstrates the existence of stable bouncing cosmological solutions within Teleparallel Horndeski gravity, effectively violating the no-go theorem and avoiding instabilities present in previous NEC-violating models.

Contribution

It introduces stable bouncing solutions in Teleparallel Horndeski gravity, providing a viable alternative to traditional models that face instabilities.

Findings

Existence of stable NEC-violating bouncing solutions

Explicit construction of healthy solutions in Teleparallel Horndeski gravity

Violation of the no-go theorem without instabilities

Abstract

In order to have singularity-free solutions at the beginning of the Universe, we need to violate the null energy condition. In the general class of Horndeski gravity, there are healthy NEC-violating solutions, which however are plagued with instabilities or some kind of pathologies in the history of the Universe; this is known as the no-go theorem. In this paper, we study the possibility of stable bouncing solutions in the Teleparallel analog of Horndeski gravity and we show explicitly that there exist healthy violations of the no-go theorem.