Two-photon contribution to the $K_L\to {\mu }^{+}{\mu }^{-}$ decay amplitude from a $1/a\approx 1$ GeV lattice

En-Hung Chao, Ceran Hu

We present a lattice-QCD calculation of the long-distance two-photon contribution to the decay amplitude of a long-lived kaon to a pair of muons on a $24^3\times 64$ physical-pion-…