Marginal IR running of Gravity as a Natural Explanation for Dark Matter

We propose that the infrared (IR) running of Newton's coupling provides a simple and universal explanation for large--distance modifications of gravity relevant to dark matter phenomenology. Within the effective field theory (EFT) framework, we model $G(k)$ as a scale--dependent coupling governed by an anomalous dimension $η$. We show that the marginal case $η= 1$ is singled out by renormalization group (RG) and dimensional arguments, leading to a logarithmic potential and a $1/r$ force law at large distances, while smoothly recovering Newtonian gravity at short scales. The logarithmic correction is universal and regulator independent, indicating that the $1/r$ force arises as the robust IR imprint of quantum--field--theoretic scaling. This provides a principled alternative to particle dark matter, suggesting that galactic rotation curves and related anomalies may be understood as manifestations of the IR running of Newton's constant.