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arXiv · 2608.12003

Emergent scalar field dynamics in a cosmological spacetime from GFT quantum gravity

Roukaya Dekhil·Federico Greco·Stefano Liberati·Daniele Oriti
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Abstract

We derive an effective scalar field theory for matter in group field theory condensate cosmology, starting from the fundamental quantum-gravity dynamics in a fully relational framework and encompassing both early- and late-universe regimes. The collective hydrodynamics of the underlying quantum geometry allows us to reconstruct both the homogeneous cosmological dynamics of matter and geometry and an inhomogeneous local field-theory description. Localization in space and time is defined relationally with respect to a material reference frame. At the homogeneous level, we obtain a modified scalar field theory on the emergent FLRW spacetime selected by the condensate. It recovers the standard dynamics of a massless scalar field in the late-time general-relativistic regime while retaining quantum-gravity corrections near the cosmological bounce. At the perturbative level, scalar inhomogeneities obey an effective wave equation that carries signatures of the underlying quantum-gravity microstructure. In the early-universe regime, this equation exhibits a modified dispersion relation with both dispersive and dissipative contributions. These corrections provide a concrete avenue for identifying phenomenological signatures of quantum gravity directly from a fundamental quantum-gravity framework.

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Roukaya Dekhil, Federico Greco, Stefano Liberati, Daniele Oriti. 2026-08-12. Emergent scalar field dynamics in a cosmological spacetime from GFT quantum gravity. https://arxiv.org/abs/2608.12003

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