The Fellowship of the Curvatures: f(R) meets Gauss-Bonnet

Wednesday 29 Oct 2025, 12:30 → 14:00 Europe/Rome

Marconi Building, Sala Fiore

General Relativity is expected to break down in the high-curvature regime. Beyond effective field theories with higher-order operators, it is crucial to identify consistent nonperturbative theories including higher-curvature terms. Two well-studied cases are f(R) gravity and Einstein–dilaton–Gauss–Bonnet (EdGB) gravity. The former shares GR’s vacuum solutions, while the latter faces well-posedness issues in the strong-coupling regime. We show that combining them yields genuinely new phenomena beyond simple superposition. This framework naturally extends EdGB gravity to include arbitrary higher-curvature terms. Focusing on quadratic and quartic corrections, we find: (i) black holes are modified by f(R) terms, unlike in pure EdGB; (ii) the solutions preserve key nonperturbative EdGB features, such as minimum mass and multiple branches; (iii) a mechanism suppresses Ricci-scalar divergence in the interior; yet (iv) the singularity and elliptic regions remain similar to EdGB. Thus, adding higher-order terms does not resolve the theory’s ill-posedness at the nonperturbative level (based on: arXiv:2510.17965)