Cosmological implications of interacting Group Field Theory models: cyclic Universe and accelerated expansion

TL;DR

This paper explores how interactions in Group Field Theory lead to cyclic cosmological models with a bounce and an accelerated expansion phase, providing a quantum gravity-based explanation for early universe phenomena.

Contribution

It demonstrates that GFT interactions naturally produce cyclic universes and prolonged accelerated expansion without additional assumptions or potentials.

Findings

GFT interactions cause universe recollapse while maintaining a bounce.

Cyclic cosmologies emerge without predefined spatial geometry.

Interactions enable prolonged accelerated expansion without scalar field potentials.

Abstract

We study the cosmological implications of interactions between spacetime quanta in the Group Field Theory (GFT) approach to Quantum Gravity from a phenomenological perspective. Our work represents a first step towards understanding Early Universe Cosmology by studying the dynamics of the emergent continuum spacetime, as obtained from a fundamentally discrete microscopic theory. In particular, we show how GFT interactions lead to a recollapse of the Universe while preserving the bounce replacing the initial singularity, which has already been shown to occur in the free case. It is remarkable that cyclic cosmologies are thus obtained in this framework without any a priori assumption on the geometry of spatial sections of the emergent spacetime. Furthermore, we show how interactions make it possible to have an early epoch of accelerated expansion, which can be made to last for an arbitrarily large number of e-folds, without the need to introduce an ad hoc potential for the scalar field.