Self-consistent reheating in modified gravity

Develop a fully self-consistent reheating framework for inflation realized in modified gravity theories, specifying concrete decay channels from geometric degrees of freedom (e.g., curvature, torsion, non-metricity, Gauss–Bonnet couplings) to radiation and matter, and determining the associated reheating temperature, efficiency, and equation-of-state evolution across representative f(R), f(T), f(Q), scalar–Gauss–Bonnet, and related models.

Background

In the review’s survey of post-inflation dynamics, the authors emphasize that reheating in many modified gravity scenarios lacks a unified and predictive treatment. While Starobinsky f(R) inflation has a well-studied scalaron decay mechanism, other frameworks (teleparallel f(T), symmetric teleparallel f(Q), scalar–Gauss–Bonnet couplings, mimetic gravity, etc.) do not yet have a robust and broadly accepted reheating prescription.

This gap affects both theoretical consistency (e.g., mapping geometric energy into thermalized radiation) and phenomenology (e.g., determining N* and links to CMB observables). The authors identify the need for model-independent criteria and concrete mechanisms applicable across the modified gravity landscape.