The separate universe framework in group field theory condensate cosmology

TL;DR

This paper applies the separate universe framework within group field theory to model quantum gravity cosmology, deriving equations that match classical results and include quantum corrections near the Planck scale.

Contribution

It introduces a novel approach combining the separate universe framework with group field theory condensates to study cosmological perturbations.

Findings

Equations of motion align with classical general relativity in the classical limit.

Quantum gravity corrections become significant at high curvature.

Multi-condensate states represent cosmological space-times with small perturbations.

Abstract

We use the separate universe framework to study cosmological perturbations within the group field theory formalism for quantum gravity, based on multi-condensate quantum states. Working with a group field theory action for gravity minimally coupled to four scalar fields that can act as a set of relational clock and rods, we argue that these multi-condensate states correspond to cosmological space-times with small long-wavelength scalar perturbations. Equations of motion for the cosmological perturbations are derived, which in the classical limit agree with the standard results of general relativity and also include quantum gravity corrections that become important when the space-time curvature approaches the Planck scale.