Abstract

Rare heavy meson decays, e.g. B → K* mu mu, provide an ideal opportunity to test the Standard Model. Any tension between experimental measurements of these decays and their predicted values gives insight into new physics, beyond the Standard Model. Lattice QCD has proven to be a remarkably powerful tool for determining the non-perturbative QCD contribution to leptonic and semileptonic decays of hadrons. Until just recently, however, it was not clear how to study processes such as the one mentioned above, where the initial or final state contains particles that are unstable in QCD . In this talk I will review the challenges faced here, as first observed by Maiani and Testa. I will present new formalism that allows one to determine one-to-two transition form factors from Lattice QCD . Finally, I will discuss how this can be implemented to study B → K*, properly dealing with the resonance nature of the final state.