Evidence for a Scale-Dependent Effective Gravitational Response from Redshift-Space Distortions

Description This work presents an effective field theory–inspired test of a scale-dependent gravitational response using current redshift-space distortion (RSD) measurements of the growth rate f\sigma_8(z). A Yukawa-like modification of the Poisson kernel is implemented directly at the level of particle-mesh N-body simulations, leaving the background cosmology and initial conditions unchanged. The modified model is confronted with observational RSD data over the redshift range 0.3 \lesssim z \lesssim 1.5, and compared against the standard Newtonian prediction within \LambdaCDM using \chi^2, AIC, and BIC criteria. We find that a finite-range, scale-dependent gravitational response provides a statistically significant improvement over standard gravity, driven by a change in the scale dependence of the growth rate rather than a simple rescaling of its amplitude. This preprint represents an independent phenomenological and numerical analysis and is part of a broader research program exploring effective modifications of gravity on quasi-linear scales. “The benchmark EFT model yields a substantial improvement over standard Newtonian gravity, with a ΔBIC exceeding 40 depending on the redshift range, indicating strong statistical preference despite the minimal extension.”