B meson decays using heavy HISQ b quarks

标准模型对夸克变味相互作用的调节包括先验未知变量，CKM矩阵的元素，这些变量参数化了我们对夸克变味相互作用的基础物理的无知。此外，通过几十年的实验和理论努力确定的CKM矩阵的值揭示了一种无法解释的结构，表明自然界遵守了一套未知的规则，但不是我们标准模型的一部分。详细研究这种衰变可能有助于阐明这些规则并发现新的物理定律。这个项目的工作在这个方向上，通过改进强子矩阵元的计算所需的提取CKM矩阵元，相关的B介子衰变，从实验测量。这不仅对发现潜在的新物理学所起的作用很重要，而且因为我们利用实验结果的能力取决于类似的精确计算。在未来的几年里，欧洲核子研究中心的大型强子对撞机B将继续获得B介子衰变的新结果。与此同时，日本超级KEK加速器设施的Belle-II探测器将收集前所未有的B介子衰变数据。使用从头算方法称为格点QCD，我们计算所需的强子矩阵元素，这些衰变。格点QCD是唯一可以用来计算这些非微扰矩阵元的工具，而不必求助于非受控近似。我们将使用一种在格拉斯哥发展起来的方法，以完全相对论的方式处理B夸克，从而消除目前在晶格上计算B介子时系统不确定性的主要来源。初步结果表明，该计划将是成功的，并且可以减少误差，使格点QCD结果的精度与实验结果相匹配或超过。

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.