Speaker
Description
The decay of a long-lived kaon to a pair of muons (KL2mu) could serve as a precision test of the Standard Model (SM) and a probe to physics beyond due to its sensitivity to physics at high energies. A precise determination of the size of the long-distance, two-photon contribution to KL2mu -- as well as its interference with the analytically-computable short-distance (SD) contribution -- are crucial for making a meaningful comparison between the SM prediction and experiment. In this talk, I will present the ongoing effort from the RBC/UKQCD collaboration to extract the two-photon decay amplitude of KL2mu using Lattice Quantum Chromodynamics. Both the size and the relative sign of the two-photon KL2mu decay amplitude with regard to its SD counterpart can be determined unambiguously from first principles with an accuracy of at least 10%. I will also discuss how to extend our framework to determine the CP-conserving two-photon contribution to the decay amplitude of a long-lived kaon into a neutral pion and a pair of muons.