Cosmic Acceleration from Quantum Gravity: Emergent Inflation and Dynamical Dark Energy

We present a mechanism for the emergence of cosmic acceleration within the mean-field approximation of Group Field Theory models of quantum gravity. Depending on the interaction type, the resulting cosmological dynamics can either feature a late-time attractor corresponding to a dynamical dark energy phase, often with characteristic phantom behavior, including in models inspired by simplicial gravity, or instead support an early slow-roll inflationary epoch driven by the same underlying quantum-gravitational effects. This emergent inflation, effectively captured by a single-field description, can sustain the required expansion, naturally avoids the graceful exit problem, and appears to transition into a persistent, non-accelerating phase consistent with classical expectations.

💡 Research Summary

The paper investigates how cosmic acceleration—both the late‑time dark‑energy driven expansion and the early‑time inflationary burst—can emerge naturally from the mean‑field dynamics of Group Field Theory (GFT), a background‑independent approach to quantum gravity. The authors work within the condensate formalism, where a macroscopic quantum state of many GFT quanta is described by a complex mean field σ(χ)=ρ(χ) e^{iθ(χ)}. The relational scalar field χ serves as a clock, allowing the dynamics of ρ and θ to be expressed as ordinary differential equations in relational time.

Starting from a generic GFT action, the mean‑field equation takes the form L