LAUSR

The nucleon spin-averaged forward virtual Compton tensor determines important physical quantities such as electromagnetically-induced mass differences of nucleons, and two-photon exchange contributions in hydrogen spectroscopy. It depends on two kinematic variables: $$\nu$$, the virtual photon energy in the proton rest frame, and $Q^2$, the photon's invariant four-momentum squared. Using the operator product expansion, we calculate the tensor's large-$Q^2$ behavior for $$\nu=0$$, including for the first time the full spin-2 contribution and correcting a previous result for the spin-0 contribution. Implications for the proton radius puzzle are discussed.