Finite-volume effects in long-distance processes with massless leptonic propagators

Understand

In Ref.

• [1], a method was proposed to calculate QED corrections to hadronic self energies from lattice QCD without power-law finite-volume errors.
• In this paper, we extend the method to processes which occur at second-order in the weak interaction and in which there is a massless (or almost massless) leptonic propagator.
• We demonstrate that, in spite of the presence of the propagator of an almost massless electron, such an infinite-volume reconstruction procedure can be used to obtain the amplitude for the rare kaon decay $K^+\to\pi^+\nu\bar\nu$ from a lattice quantum chromodynamics computation with only exponentially small finite-volume corrections.