Hadron Spectroscopy in the Light Quark Sector at GlueX

GlueX 光夸克领域的强子光谱

• 批准号: SAPPJ-2022-00023
• 负责人: Papandreou, Zisis
• 金额: $ 12.02万
• 依托单位: University of Regina
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762547
• 关键词: Hadron; Spectroscopy; Light; Quark; Sector

Subatomic physics seeks to understand nature - and all its laws - at the most fundamental level, down to its elementary constituents and their interactions. Tremendous strides have been made in the last several decades, using accelerators and astrophysical observations, which have strengthened our conviction that the basic model, known as the Standard Model, is essentially a valid description of the subatomic world but not necessarily a complete one. Among the four forces of the Standard Model, the strong force inside an atomic nucleus is understood by a theory called Quantum Chromodynamics (QCD). QCD describes the physics underlying the interaction of quarks and gluons and it seems to permit a rich spectrum of allowed constituents, whereas nature prefers to reveal a narrower set of quark and gluonic composite states. Features of QCD include six flavors of quarks with various masses, strongly interacting quarks and gluons, and the phenomena of asymptotic freedom and confinement. To date only colourless "quark model" states have been observed - such as quark-antiquark pairs (mesons) and quark triplets (baryons) - while gluonic degrees of freedom are difficult to observe or suppressed. But QCD predicts more types of states than just mesons and baryons. The goal of the GlueX Experiment is to produce and identify unseen exotic forms of matter that exhibit unique signatures among all other particles, which will allow QCD to be tested in a constraining manner. Specifically, hybrid mesons result from the addition of gluon quantum numbers to those of the quarks and a subset of hybrids is predicted to have exotic quantum number combinations that are not allowed in the simple quark model. This is a difficult task requiring experimental conditions that have recently become possible in accelerator and detector technology. GlueX is addressing the former by employing a unique, high-intensity, polarized photon beam and a hermetic detector. The latter has benefited by the recent development of large silicon-based photo sensors that are completely immune to magnetic fields. Our group played a defining role in guiding industry towards their development and these devices are now available commercially to the subatomic, medical and nuclear safety fields. The GlueX plan is to map out the QCD spectrum by systematically studying all decay modes of conventional and hybrid mesons. This effort needs to reconcile state-of-the-art experimental results with state-of-the-art experimental interpretation. The latter is limited by uncertainties in obtaining a robust theoretical description rather than our understanding of the detector or the statistical precision of the data. Our group will pursue the analysis of low-mass mesons, in regions where there is sparse or no real-world data. This research will provide data in controversial (past experiments with low statistical power) as well as unexplored domains of meson spectroscopy.

亚原理在最基本的层面上试图理解自然及其所有定律，直到其基本成分及其相互作用。在过去的几十年中，使用加速器和天体物理学观察取得了长足的进步，这加强了我们坚信的信念，即基本模型（称为标准模型）实质上是对亚原子世界的有效描述，但不一定是完整的。在标准模型的四个力中，原子核内部的强力通过称为量子染色体动力学（QCD）的理论来理解。 QCD描述了夸克和胶子相互作用的物理学，它似乎可以允许丰富的允许成分，而自然则倾向于揭示一组狭窄的夸克和gluonic复合状态。 QCD的特征包括六种具有各种质量的夸克风味，强烈相互作用的夸克和胶子，以及渐近自由和约束的现象。迄今为止，仅观察到了无色的“夸克模型”状态，例如夸克 - 易夸克对（介子）和夸克三重态（Baryons） - 而gluonic自由度很难观察或抑制。但是，QCD不仅仅是介子和重子，QCD可以预测更多的状态。 Gluex实验的目的是生产和确定所有其他粒子之间表现出独特特征的看不见的外来物质形式，这将使QCD可以以约束方式进行测试。具体而言，混合介子是由于向夸克的添加Gluon量子数而导致的，并且预计混合动力的子集将具有在简单的夸克模型中不允许的外来量子数组合。这是一项艰巨的任务，需要实验条件最近在加速器和检测器技术中成为可能。 Gluex通过采用独特的高强度，极化光子束和密封检测器来解决前者。最近的大型基于硅光子传感器的开发使后者受益，这些传感器完全不受磁场的影响。我们的小组在指导行业发展其发展方面发挥了重要作用，这些设备现在可以商业地用于亚原子，医疗和核安全领域。 Gluex计划是通过系统地研究所有常规介子和混合介子的衰减模式来绘制QCD频谱。这种努力需要将最新的实验结果与最先进的实验解释调和。后者受到不确定性获得可靠的理论描述的限制，而不是我们对检测器或数据的统计精度的理解。我们的小组将在稀疏或没有现实世界数据的地区进行低质量介子的分析。这项研究将提供有争议的数据（过去具有低统计能力的实验）以及未开发的梅森光谱域。