Let us work with charge renormalization in QED. Consider 2-point photon correlation function $\Pi_2(q^2)$ at one loop level. We normalize the coupling constant at $q^2=0$ (point of normalization). What is the effective coupling constant $e(q^2)$ at $−q^2 ≫ m^2$ at one loop level. Does coupling constant decrease or increase with $q^2$?