Applications of QCD in the Standard Model and Beyond

这项拨款提案涉及的工作旨在阐明粒子物理学标准模型的动力学，既包括标准模型本身的背景，也包括确定标准模型对目前正在调查的过程的贡献的背景，这些过程是目前正在进行的、正在进行的、在世界各地的主要实验设施中正在进行或即将开始的对标准模型之外的物理学的实验搜索的一部分。在这些过程中，精确理解标准模型的贡献对于昂贵的实验项目的成功至关重要，因为如果要确定超出标准模型的效应，就必须彻底准确地理解这些贡献的背景。******在这方面特别重要的是确定强相互作用的影响，因为它们的强度(1)可以非常具有数值意义，(2)与较弱的电磁和弱相互作用产生的影响相比，可以使用更有限的理论技术进行处理。强相互作用效应将使用量子色动力学（QCD）来评估，量子色动力学是强（核和亚核）相互作用的理论，采用了许多严格的、成熟的理论技术，包括大规模数值模拟（晶格QCD）。我们将使用这些技术，结合来自各种对撞机设备的实验数据，对标准模型参数进行最先进的确定，例如强相互作用耦合的强度和上奇卡比博-小林- maskawa矩阵元素，该参数描述了包含奇异夸克的强子态衰变为奇异夸克转换为上夸克的状态的速度。鉴于目前的迹象表明，弱相互作用可能以不同的强度与不同的轻子耦合，这种可能性将为标准模型之外的物理存在提供明确的证据，因此，基于重的tau轻子的奇怪强子衰变，对后一个量的新确定尤其令人感兴趣。我们还将继续以前的工作，寻找新的（“外来的”）强子物质的状态。******该提案的部分工作还包括创建一套计算机程序，使日本新建的主要Belle II设施的实验人员能够对tau轻子强子衰变的实验数据进行理论的、基于qcd的分析，这些数据将作为Belle II设施多年计划的一部分产生，预计将于2018年开始物理运行。因此，这项拨款提案中的工作也将有助于提高粒子理论家和实验家之间合作的效率。*****

This grant proposal involves work aimed at elucidating the dynamics of the Standard Model of particle physics, both in the context of the Standard Model itself, and in the context of determinations of Standard Model contributions to processes currently under investigation as part of the intensive, ongoing experimental search for physics beyond the Standard Model either underway at present, or about to start, at major experimental facilities throughout the world. In these processes, a precision understanding of Standard Model contributions is crucial to the success of the very expensive experimental programs since these contributions serve as backgrounds which must be thoroughly and precisely understood if beyond-the-Standard-Model effects are to be identified. ******Of particular importance in this regard is the determination of the effects of the strong interactions, which, because of their strength (1) can be very numerically significant and (2) are amenable to treatment using a much more limited set of theoretical techniques than are effects produced by the weaker electromagnetic and weak interactions. Strong interaction effects will be evaluated using Quantum Chromodynamics (QCD), the theory of the strong (nuclear and sub-nuclear) interactions, employing a number of rigorous, well-established theoretical techniques, including large scale numerical simulations (lattice QCD). We will use these techniques, in combination with experimental data from various collider facilities, to make state-of-the-art determinations of Standard Model parameters such as the strength of the strong interaction coupling and the up-strange Cabibbo-Kobayashi-Maskawa matrix element, a parameter which describes how rapidly a hadronic state containing a strange quark can decay into states in which the strange quark has been converted into an up quark. A new determination of this latter quantity based on the strange hadronic decays of the heavy tau lepton is of particular interest in view of current indications of the possibility that the weak interactions couple with different strengths to the different leptons, a possibility that would provide unambiguous evidence for the presence of physics beyond the Standard Model. We will also continue previous work on looking for novel ("exotic") states of hadronic matter.******Part of the work involved in this proposal will also involve creating a suite of computer programs which will allow experimentalists at the new major Belle II facility in Japan to perform theoretical, QCD-based analyses of experimental data on hadronic decays of the tau lepton that will be generated as part of the multi-year program at the Belle II facility, expected to begin physics runs in 2018. The work in this grant proposal will thus also serve to increase the effectiveness of the collaboration between particle theorists and experimentalists.*****