Search for Physical States with Gluonic Excitations in the Light Quark Sector

寻找光夸克扇区中具有胶子激发的物理状态

• 批准号: SAPPJ-2018-00021
• 负责人: Papandreou, Zisis
• 金额: $ 10.64万
• 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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=718936
• 关键词: Search; Physical; States; Gluonic; Excitations

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 described by a theory called Quantum Chromodynamics (QCD). QCD describes the physics underlying the interaction of quarks and gluons and it predicts a virtual “zoo” of particles and resonances. To date only colorless “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, by their very nature, exhibit unique signatures among all other particles that will allow QCD to be tested in a most constraining way possible. 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 are just now becoming 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 full QCD spectrum by systematically studying all possible decay modes of conventional and hybrid mesons while carrying out quantum-number and decay-channel strength measurements. 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.

亚原子物理学试图从最基本的层面理解自然及其所有定律，直至其基本成分及其相互作用。在过去的几十年里，使用加速器和天体物理观测取得了巨大的进步，这增强了我们的信念，即称​​为标准模型的基本模型本质上是对亚原子世界的有效描述，但不一定是完整的描述。在标准模型的四种力中，原子核内部的强力是由量子色动力学（QCD）理论来描述的。 QCD 描述了夸克和胶子相互作用的物理原理，并预测了粒子和共振的虚拟“动物园”。迄今为止，仅观察到无色的“夸克模型”态，例如夸克-反夸克对（介子）和夸克三重态（重子），而胶子自由度很难观察或抑制。但 QCD 预测的态类型不仅仅是介子和重子。 GlueX 实验的目标是产生和识别看不见的奇异物质形式，这些物质就其本质而言，在所有其他粒子中表现出独特的特征，这将使 QCD 能够以最严格的方式进行测试。具体来说，混合介子是由胶子量子数与夸克量子数相加而产生的，并且混合介子的子集预计具有简单夸克模型中不允许的奇异量子数组合。 这是一项艰巨的任务，需要实验条件，而加速器和探测器技术现在才成为可能。 GlueX 通过采用独特的高强度偏振光子束和密封探测器来解决前者。后者受益于最近开发的完全不受磁场影响的大型硅基光电传感器。我们的团队在引导行业发展方面发挥了决定性作用，这些设备现已在亚原子、医疗和核安全领域投入商业应用。 GlueX 计划是通过系统地研究传统介子和混合介子的所有可能的衰变模式，同时进行量子数和衰变通道强度测量，来绘制完整的 QCD 谱。我们的小组将在现实世界数据稀疏或没有的地区进行低质量介子分析。这项研究将提供有争议的（过去统计功效较低的实验）以及未探索的介子光谱领域的数据。