Precise Standard Model corrections to New Physics searches with unitarity tests of the Cabibbo-Kobayashi-Maskawa quark mixing matrix

通过 Cabibbo-Kobayashi-Maskawa 夸克混合矩阵的幺正性测试对新物理搜索进行精确的标准模型修正

• 批准号: 495329596
• 负责人: Dr. Mikhail Gorshteyn
• 金额: --
• 依托单位: Institut für Kernphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/495329596?language=en
• 关键词: Precise; Standard; Model; corrections; New

Discovery of the Higgs boson has completed the quest for the particles that were predicted by the Standard Model (SM), required by its symmetries and breaking thereof. Extremely successful in particle physics, SM fails to describe a body of cosmological observations, which motivates searches for hidden particle and interaction sectors beyond SM (BSM). If new heavy particles are present in nature, they should become visible at the energy frontier reachable with colliders. Although the LHC operates at unprecedentedly high energies, no signs of BSM have been observed. Future colliders will expand the energy frontier horizons.Surprisingly, hints to possible BSM signals are observed at lower energies. The magnetic moment of the muon is 4.2σ away from the SM theory prediction, while an agreement for the electron is observed. Semileptonic B-meson decays exhibit a 4σ departure from lepton flavor universality. Universality of weak interaction is reflected in unitarity of the Cabibbo- Kobayashi-Maskawa (CKM) quark mixing matrix yet the measurements combine to a 3σ unitarity deficit.This deficit may be interpreted as an effect of heavy BSM physics which is probed by the LHC and β decays in a complementary and competitive way. Upcoming β decay experiments with improved precision will maintain this complementarity in the following years. To empower this sensitivity to BSM, precise theoretical calculations of SM correctionsare vital. Due to confinement, weak processes involving quarks are only accessible with their bound states, hadrons. Quantum Chromodynamics (QCD) that describes this binding and the properties of the compound is very complex and a perturbation expansion at low energies has only limited applicability. Our ability to reliably compute effects of strong interaction is central to the interpretation of low-energy precision tests.This project is dedicated to hadronic and nuclear structure effects in the determination of the top left corner CKM matrix element Vud. These effects cannot be distinguished from BSM signals experimentally, and need to be subtracted from the results of the experimental analyses. This puts forth the requirement of controlling theoretical uncertainties.I am a widely recognized expert in the theory of electroweak box diagrams where I developed the dispersion relation framework that fulfills this requirement and is now considered the state-of-the-art. The innovative research proposed here builds upon this expertise and is enriched by the cooperation with experts on nuclear theory and radiative corrections. It will deliver crucial theoretical ingredients for constraining BSM with CKM unitarity, with a potential of a BSM discovery, and will open up new research avenues.

希格斯玻色子的发现完成了对标准模型（SM）所预测的粒子的探索，这是标准模型的对称性和破缺性所必需的。虽然SM在粒子物理学上取得了极大的成功，但它未能描述宇宙观测的整体，这促使人们在SM （BSM）之外寻找隐藏的粒子和相互作用领域。如果自然界中存在新的重粒子，它们应该在对撞机可以到达的能量边界上可见。尽管大型强子对撞机以前所未有的高能量运行，但没有观测到BSM的迹象。未来的对撞机将扩大能量前沿的视野。令人惊讶的是，可能存在BSM信号的迹象是在较低的能量下观测到的。μ子的磁矩与SM理论的预测值相差4.2σ，而电子的磁矩与SM理论的预测值一致。半光子b介子衰变表现出与轻子味普适性的4σ偏差。弱相互作用的普适性反映在Cabibbo- Kobayashi-Maskawa （CKM）夸克混合矩阵的统一性上，但测量结果却存在3σ的统一性缺陷。这种缺陷可以解释为LHC探测的重BSM物理和β衰变以互补和竞争的方式产生的影响。在接下来的几年里，精度更高的β衰变实验将保持这种互补性。为了增强对BSM的敏感性，精确的SM校正理论计算至关重要。由于约束，涉及夸克的弱过程只有在它们的束缚态——强子——下才能进行。描述这种结合和化合物性质的量子色动力学（QCD）非常复杂，低能微扰展开的适用性有限。我们可靠地计算强相互作用效应的能力是解释低能量精确测试的核心。本项目致力于强子和核结构效应在左上角CKM矩阵元素Vud的测定。这些效应不能从实验中与BSM信号区分开来，需要从实验分析的结果中减去。这就提出了控制理论不确定性的要求。我是公认的电弱箱图理论专家，我开发了色散关系框架，满足了这一要求，现在被认为是最先进的。这里提出的创新研究建立在这种专门知识的基础上，并通过与核理论和辐射校正专家的合作而丰富。它将为约束具有CKM统一性的BSM提供关键的理论成分，具有发现BSM的潜力，并将开辟新的研究途径。