Reheating embedded in quantum gravity

Embed the reheating phase of modified gravity inflation into a fully quantized theory of spacetime by deriving gravitational reheating dynamics in loop quantum cosmology, string field theory, or under asymptotic safety, and quantify their observational consequences.

Background

While phenomenological reheating models exist, the review stresses the absence of a derivation anchored in a complete quantum gravity framework. Such an embedding would clarify energy transfer mechanisms and resolve ambiguities about initial conditions and particle production.

A quantum-gravity-based description could also produce distinct signatures (e.g., GW backgrounds) that test the microphysics of early-universe reheating.

References

We highlight several key open problems: Can the reheating phase—often treated phenomenologically—be embedded within a fully quantized theory of spacetime? For example, how does gravitational reheating operate in loop quantum cosmology, string field theory, or under asymptotic safety constraints?

— From geometry to cosmology: a pedagogical review of inflation in curvature, torsion, and extended gravity theories  (2509.14306 - Momeni, 17 Sep 2025) in Section: Open Questions and Future Directions

Similar results are expected in higher dimensions, although they have not been checked explicitly.

— Logarithmic gravity from a very slow roll limit of inflation  (2609.38052 - Cotler et al., 29 Sep 2026) in Introduction, paragraph beginning “The origin of this cancellation can be understood by considering the cutoff.”