Applications of QCD in the Standard Model and Beyond

这项赠款提案涉及旨在阐明粒子物理标准模型的动力学的工作，这既包括标准模型本身，也包括确定标准模型对目前正在研究的过程的贡献，这是目前世界各地主要实验设施正在进行或即将开始的对标准模型以外的物理的深入、持续的实验研究的一部分。在这些过程中，对标准模型贡献的准确理解对非常昂贵的实验计划的成功至关重要，因为这些贡献作为背景，如果要识别超出标准模型的效应，必须彻底和准确地理解这些背景。*在这方面特别重要的是确定强相互作用的影响，由于它们的强度，(1)在数字上可能非常重要，(2)与较弱的电磁和弱相互作用产生的影响相比，可以使用一套更有限的理论技术进行治疗。强相互作用效应将使用量子色动力学(QCD)，即强(核和亚核)相互作用理论，使用一些严格的、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，来确定最先进的标准模型参数，如强相互作用耦合的强度和上奇异Cabibbo-Kobayashi-Maskawa矩阵元，该参数描述了包含奇异夸克的强子态衰变到奇异夸克转化为上夸克的状态的速度。考虑到目前有迹象表明，弱相互作用可能会以不同的强度耦合到不同的轻子，基于重牛轻子奇怪的强子衰变来确定后一个量，这一可能性将为标准模型以外的物理存在提供明确的证据。我们还将继续之前的工作，寻找强子物质的新颖(“奇异”)状态。*这项提议涉及的工作还包括创建一套计算机程序，使日本新的主要Belle II设施的实验者能够对有关tau轻子强子衰变的实验数据进行理论上的、基于QCD的分析，这将是Belle II设施多年计划的一部分，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学家之间合作的有效性。

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.*****