Fifth-Force Constraints from UV-Complete Scalar-Tensor Gravity

We study an $O(N)$ scalar multiplet nonminimally coupled to gravity and follow its renormalization-group (RG) flow in the vicinity of an interacting, nonperturbatively UV-complete scaling regime of scalar-tensor theory. In the broken phase, the radial mode mediates a universal Yukawa correction to Newtonian gravity, parametrized by a strength $\alpha$ and range $\lambda$. Imposing UV completeness – regular RG trajectories that reach the UV scaling regime – restricts the infrared data to a finite wedge, which maps to a narrow region in the $(\alpha ,\lambda )$ plane. Its complement is, therefore, ruled out by UV completeness alone. Remarkably, part of this theory-excluded domain lies below current experimental exclusion envelopes, so improved fifth-force searches can directly test and potentially falsify this class of UV-complete scalar-tensor models.