Light-front holographic QCD and exclusive B decays

光前全息 QCD 和独特的 B 衰变

• 批准号: SAPIN-2017-00031
• 负责人: Sandapen, Ruben
• 金额: $ 1.09万
• 依托单位: Mount Allison University
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=617857
• 关键词: Light; front; holographic; QCD; exclusive

The Standard Model (SM) of particle physics has successfully withstood decades of intensive testing culminating in the long-awaited discovery of the Higgs boson in 2012 at the LHC. Yet, we know that the SM is incomplete since it does not accommodate gravity and neither does it account for neutrino oscillations, dark matter and for the matter/antimatter asymmetry. Despite intensive efforts, to this date no New Physics (NP) discoveries have been made at the LHC. However, an intriguing number of anomalies, i.e. discrepancies between the data and SM predictions, have been reported in rare exclusive B decays. These are decays of the B meson (containing a heavy b quark) to a lighter meson (no b quark) accompanied by a photon or a pair of leptons. These exclusive decays are relatively clean to measure experimentally but the theory behind them is challenging. There are two reasons for this: first, although we are able to compute (using perturbation theory) the underlying b-quark decay in the SM, our final predictions for observables have a residual dependence on an energy scale called the renormalization scale thus introducing a systematic uncertainty. Secondly, quarks and gluons are permanently confined into mesons and this has to be carefully accounted for using non-perturbative methods.

粒子物理学的标准模型（SM）成功地在2012年在LHC上发现了人们期待已久的希格斯玻色子（Higgs Boson）的几十年进行了深入的测试。然而，我们知道SM不完全不适合重力，并且它也无法解释中微子振荡，暗物质和物质/反物质不对称。尽管进行了密集的努力，但此日还没有在LHC上发现新的物理（NP）。但是，在罕见的B衰减中，已经报道了许多有趣的异常，即数据和SM预测之间的差异。这些是B Meson（包含重B夸克）的衰变，伴有光子或一对瘦素。这些独家衰减相对干净，可以实验测量，但是它们背后的理论具有挑战性。造成两个原因有两个：首先，尽管我们能够计算SM中的基本B Quark衰减（使用扰动理论），但我们对可观察物的最终预测对称为重新归一化量表的能量量表具有残差依赖性，从而引入了系统的不确定性。其次，夸克和胶子被永久限制在介子中，必须仔细考虑使用非扰动方法。