Applications of QCD in the Standard Model and Beyond

这项资助提案涉及的工作旨在阐明粒子物理学标准模型的动力学，无论是在标准模型本身的背景下，还是在确定标准模型对目前正在调查的过程的贡献的背景下，作为目前正在进行或即将开始的对标准模型之外的物理学进行深入，持续实验研究的一部分，在世界各地的主要实验设施。在这些过程中，对标准模型贡献的精确理解对于非常昂贵的实验计划的成功至关重要，因为如果要识别超越标准模型的效应，这些贡献就必须作为背景进行彻底和精确的理解。 在这方面，特别重要的是确定强相互作用的效应，由于它们的强度（1）在数值上可能非常重要，（2）与较弱的电磁和弱相互作用产生的效应相比，可以使用更有限的一组理论技术进行处理。强相互作用效应将使用量子色动力学（QCD），强（核和亚核）相互作用的理论，采用一些严格的，完善的理论技术，包括大规模的数值模拟（格子QCD）进行评估。我们将使用这些技术，结合来自各种对撞机设施的实验数据，对标准模型参数进行最先进的测定，例如强相互作用耦合的强度和上奇异Cabibbo-Kobayashi-Maskawa矩阵元，一个参数，描述一个包含一个奇异夸克的强子态衰变到奇异夸克转变为上夸克的状态的速度夸克。基于重τ轻子的奇异强子衰变对后一个量的新测定特别有意义，因为目前的迹象表明，弱相互作用可能以不同的强度耦合到不同的轻子上，这种可能性将为标准模型之外的物理学的存在提供明确的证据。我们也将继续以前的工作，寻找新的（“异国情调”）状态的强子物质。 这项提议涉及的部分工作还将涉及创建一套计算机程序，这将使日本新的主要贝儿II设施的实验人员能够对τ轻子强子衰变的实验数据进行基于QCD的理论分析，这些数据将作为贝儿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.