QCD in the Standard Model and Beyond

这项拨款提案涉及旨在阐明粒子物理标准模型(SM)的动力学的工作，既在标准模型本身的背景下，也在确定SM对目前正在调查的过程的贡献的背景下，作为全球努力的一部分，涉及在俄罗斯、瑞士、意大利、美国、日本和中国的主要实验设施进行密集的正在进行的实验计划，以搜索标准模型以外的物理信号。在这些过程中，对SM贡献的准确理解对这些非常昂贵的实验计划的成功至关重要，因为SM贡献作为背景，如果要明确地识别超越SM的影响，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。强相互作用效应的评估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)、QCD求和规则(基于一般数学约束的一类关系)和有效低能理论。我和我的研究合作者将使用这些技术，结合来自各种对撞机设备的实验数据，来确定最先进的SM参数，如强相互作用耦合的强度和向上奇异的Cabibbo-Kobayashi-Maskawa矩阵元素，该参数描述了包含奇异夸克的强子态衰变到奇异夸克已经转换为向上夸克的状态的速度。考虑到目前的迹象表明，弱相互作用可能与电子、介子和陶子轻子的不同强度耦合，基于重的tau轻子奇怪的强子衰变，改进后一种量的确定是特别感兴趣的，这一可能性将为SM之外存在物理的存在提供明确的证据。我和其他合作者还将继续之前关于强子物质可能尚未被探测到的新颖(“奇异”)状态的理论工作。这项提案中的部分工作还将涉及创建一套计算机程序，使实验者能够对新的实验数据进行理论上的、基于QCD的分析，这些数据将作为最近在日本Belle II设施开始的多年计划的一部分而产生。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 (SM) of particle physics, both in the context of the SM itself, and in the context of determinations of SM contributions to processes currently under investigation as part of a world-wide effort, involving intensive ongoing experimental programs at major experimental facilities in Russia, Switzerland, Italy, the US, Japan and China, to search for signals of physics beyond the Standard Model. In these processes, a precision understanding of SM contributions is crucial to the success of these very expensive experimental programs since SM contributions serve as backgrounds which must be thoroughly and precisely understood if beyond-the-SM effects are to be unambiguously identified. Of particular importance in this regard is the determination of the effects of the strong interactions, which, due to 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), QCD sum rules (a class of relations based on general mathematical constraints), and effective low-energy theories. I and my research collaborators will use these techniques, in combination with experimental data from various collider facilities, to make state-of-the-art determinations of SM 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 where the strange quark has been converted into an up quark. An improved determination of this latter quantity based on the strange hadronic decays of the heavy tau lepton is of particular interest in view of current hints that the weak interactions might couple with different strengths to the electron, muon and tau lepton, a possibility that would provide unambiguous evidence for the presence of physics beyond the SM. I and other collaborators, will also continue previous theoretical work on possible not-yet-detected novel ("exotic") states of hadronic matter. Part of the work in in this proposal will also involve creating a suite of computer programs which will allow experimentalists to perform theoretical, QCD-based analyses of the new experimental data on hadronic decays of the tau lepton to be generated as part of the multi-year program which commenced recently at the Belle II facility in Japan. The work in this grant proposal will thus also serve to increase the effectiveness of the collaboration between particle theorists and experimentalists.