The Standard Model of particle physics describes how fundamental particles interact and agrees with many experimental measurements. However, there are several observations it cannot explain, including what dark matter is and why there is so much more matter than antimatter in the universe. Studying decay processes at particle accelerators like the Large Hadron Collider (LHC) is an important strategy for testing the Standard Model and searching for new fundamental physics. Any experimental measurement that disagrees with the Standard Model prediction would be a smoking gun for new physics. One interesting class of processes involves a meson (a particle composed of two quarks) decaying into a lepton, a neutrino, and a photon. The quarks inside the meson interact via quantum chromodynamics (QCD). At the low energy scale of the meson, QCD must be studied numerically using a technique called lattice QCD. This method works by putting space and time on a lattice of points, and then numerically solving the QCD path integral. In this talk, I present in-progress results towards calculating the decay rate for a particular meson using lattice QCD.