One important way of testing the Standard Model is to compare its predictions with precise experimental measurements of low energy quantities. Flavour physics is an arena which permits very precise lattice QCD calculations and clean low-energy tests. My work in this area has focused on exploring the relatively unstudied decays of bottom baryons (rather than mesons); this program is motivated by exploiting the unparalleled ability of the LHC to study Λb baryons (whose quark content is udb). This effort, begun in 2009, is now having important impact on heavy-flavor phenomenology. For example, the Standard Model Cabibbo-Kobayashi-Maskawa (CKM) parameters Vub  and Vcb that control how charged current weak interactions change b quarks into u or c quarks are traditionally determined from the decays of B mesons, either exclusively by looking at a particular decay process such as B → πlνl, or by looking inclusively at all B decays. It is a long-standing puzzle that these two approaches find values of the CKM parameters that are in significant tension with each other. The LHCb collaboration recently prioritized measurements of the rates of these baryon decays and then used our work to extract the ratio |Vub/Vcb| with world-leading precision. The result rules out a number of extensions of the Standard Model as explanations of the inclusive–exclusive discrepancy, but also poses interesting new questions that can only be answered through lattice QCD. The flavour-changing neutral current decays of the heavy Λb  baryon, are also prime candidates for searches for physics beyond the Standard Model and I am actively pursuing this research direction.