AdS/QCD holographic light-front wavefunction, diffractive vector meson production and B physics

AdS/QCD 全息光前波函数、衍射矢量介子产生和 B 物理

• 批准号: SAPIN-2017-00033
• 负责人: Ahmady, Mohammad
• 金额: $ 1.46万
• 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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=643563
• 关键词: AdS; QCD; holographic; light; front

The discovery of Higgs boson by LHC in 2012 was an important step in validating the Standard Model (SM). However, there are already tensions between certain data and theoretical calculations based on SM. To make definite conclusions from these tensions, we need to improve the accuracy of both the measurement data and theoretical calculations. With the increase in luminosity and energy LHCb Run II (2015-19) expects to, at least, quadruple its effective statistics with the data collected until 2019 and hence half the uncertainties on the current measurements. In addition, SuperKEKB, which is an upgrade project of KEKB (1998-2010) at KEK (Japan) is designed to increase the instantaneous luminosity by about a factor of 40. Along with the BELLE II detector, this next-generation B-factory will complement the exploration of New Physics beyond the Standard Model currently being carried out at the energy frontier by LHC. The physics run of SuperKEKB will start in 2017. The numerous decay channels of the B mesons (quark-antiquark bound state containing a b-quark) to light mesons (quark-antiquark bound state with no b-quark) offer the opportunity to make precision tests of the Standard Model and perhaps more interestingly, to look for signals of physics beyond the SM. Exclusive B decays to light mesons are appealing since they are relatively easy to access experimentally, especially in an environment like the LHC. On the other hand, the theory of such decays is challenging due to the strong interactions effects. The theory of strong interactions, which is called quantum chromodynamics (QCD), becomes complicated when dealing with bound-state quantities. The computation of these quantities is challenging and model-dependent. Therefore, it is very important to make SM predictions using alternative viable approaches to nonperturbative QCD. ***In this research, we focus on increasing the reliability of our theoretical predictions for the exclusive B decays on both the perturbative and non-perturbative sides. First, we use an alternative and complimentary method to model QCD bound state effects. This method is known as light-front holography (LFH) and can be used to compute the non-perturbative inputs in theoretical calculations. Second, we are apply the so-called Principle of Maximum Conformality (PMC) to reduce the scale dependence of our theoretical predictions. ***We also plan to investigate the underlying connection between LFH and chiral perturbation theory which is another successful model for describing nonperturbative QCD. One should be able to deduce this connection by matching their predictions for the same physical quantity at a common kinematical range where both models are expected to be valid.

2012年大型强子对撞机发现希格斯玻色子是验证标准模型(SM)的重要一步。然而，某些数据和基于SM的理论计算之间已经存在紧张关系。为了从这些紧张关系中得出明确的结论，我们需要提高测量数据和理论计算的准确性。随着光度和能量的增加，LHCB Run II(2015-19年)预计到2019年收集的数据将使其有效统计数据至少翻两番，从而使目前测量的不确定度减少一半。此外，SuperKEKB是KEK(日本)的KEKB(1998-2010)的升级项目，旨在将瞬时亮度提高约40倍。与Belle II探测器一起，这个下一代B工厂将补充大型强子对撞机目前在能源前沿进行的超越标准模型的新物理探索。SuperKEKB的物理运行将于2017年开始。从B介子(含b夸克的夸克-反夸克束缚态)到轻介子(不含b夸克的夸克-反夸克束缚态)的众多衰变通道提供了对标准模型进行精确测试的机会，也许更有趣的是，寻找SM以外的物理信号。独家B衰变到轻介子很有吸引力，因为它们相对容易通过实验获得，特别是在大型强子对撞机这样的环境中。另一方面，由于强相互作用的影响，这种衰变的理论是具有挑战性的。被称为量子色动力学(QCD)的强相互作用理论在处理束缚态量时变得复杂起来。这些量的计算是具有挑战性的，而且依赖于模型。因此，使用其他可行的方法对非微扰QCD进行SM预测是非常重要的。*在这项研究中，我们致力于提高我们在微扰和非微扰两方面独有的B衰变的理论预测的可靠性。首先，我们使用一种替代的和互补的方法来模拟QCD束缚态效应。这种方法被称为光前全息术(LFH)，可用于计算理论计算中的非微扰输入。其次，我们正在应用所谓的最大一致性原理(PMC)来减少我们理论预测的尺度依赖性。*我们还计划研究LFH和手征微扰理论之间的内在联系，手征微扰理论是描述非微扰QCD的另一个成功模型。人们应该能够通过在两个模型都被认为有效的共同运动学范围内匹配他们对相同物理量的预测来推断这种联系。