Gielen, S. orcid.org/0000-0002-8653-5430 and Santacruz, R. (2023) Stationary cosmology in group field theory. Physical Review D, 108 (2). 026001. ISSN 2470-0010
Abstract
Group field theory (GFT) models for quantum gravity coupled to a massless scalar field give rise to cosmological models that reproduce the (expanding or contracting) dynamics of homogeneous and isotropic spacetimes in general relativity at low energies, while including high-energy corrections that lead to singularity resolution by a “bounce.” Here we investigate two possibilities for obtaining stationary solutions in GFT cosmology, which could be useful as an analog of Minkowski spacetime. We first focus on a limit in which interactions are neglected and the effective Newton’s constant in GFT cosmology is taken to zero. In this limit, we derive an effective Friedmann equation that shows no stationary solutions but departures from the trivial classical dynamics falling off rapidly, similar to the usual correction terms responsible for the bounce. Since the effective Newton’s constant needs to be exactly zero, the scenario is fine-tuned. A more satisfactory approach is obtained in a weakly interacting model: we find bound states with sharply peaked volume, representing a stationary semiclassical cosmology, and show that coherent states peaked around the minimum of the potential remain stable with small quantum fluctuations, and only small oscillations around a nearly constant volume. These coherent states realize the idea of a “quantum gravity condensate.”
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Authors. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Cosmology; Quantum cosmology; Gravitation; Quantum gravity |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Funding Information: | Funder Grant number ROYAL SOCIETY UF160662 ROYAL SOCIETY URF\R\221005 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 17 Jul 2023 11:33 |
Last Modified: | 17 Jul 2023 11:33 |
Status: | Published |
Publisher: | American Physical Society (APS) |
Refereed: | Yes |
Identification Number: | 10.1103/physrevd.108.026001 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:201608 |