QED self-energies from lattice QCD without power-law finite-volume errors

Using the infinite-volume photon propagator, we develop a method which allows us to calculate electromagnetic corrections to stable hadron masses at leading order in α QED with only exponentially suppressed finite-volume effects. The key idea is that the infinite-volume hadronic current-current correlation function with large time separation between the two currents can be reconstructed by its value at modest time separation, which can be evaluated in finite volume with only exponentially suppressed errors. This approach can be extended to many other possible applications such as QED corrections to (semi)leptonic decays and some rare decays.