B meson decays using heavy HISQ b quarks

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The Standard Model accommodation of quark flavour-changing interactions includes a priori unknown variables, the elements of the CKM matrix, that parametrize our ignorance of the underlying physics responsible for quark flavour-changing interactions. Furthermore, the values of the CKM matrix, determined by decades of experimental and theoretical effort, reveal an unexplained structure that suggests a set of unknown rules obeyed by Nature, but not part of our Standard Model. Studying such decays in detail may help to elucidate these rules and discover new laws of physics. This project works in this direction by improving the calculation of hadronic matrix elements required to extract the CKM matrix elements, related to B meson decays, from experimental measurements. This is important not only for the role played in uncovering potential new physics, but also because our ability to leverage experimental results hinges on similarly precise calculations. Over the coming years, there will continue to be new results for B meson decays from LHCb at CERN. Meanwhile, an unprecedented amount of data will be collected for decays of B mesons at the Belle-II detector at the Super KEK accelerator facility in Japan. Using an ab initio approach called Lattice QCD, we calculate the required hadronic matrix elements for these decays. Lattice QCD is the only tool available to calculate these non-perturbative matrix elements without having to resort to uncontrolled approximations. We will use an approach, developed at Glasgow, to treat the b quarks in a fully relativistic way, thereby removing the current dominant source of systematic uncertainty in B meson calculations on the lattice. Initial results suggest this program will be successful and a reduction in errors will be possible that allows the precision of lattice QCD results to match or exceed that from experiment.