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，直到其基本构成及其相互作用。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）的理论描述。 QCD描述了夸克和胶子相互作用的物理学，它预测了粒子和共振的虚拟“动物园”。迄今为止，只观察到无色的“夸克模型”状态，例如夸克式群岛对（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看不见的异国情调的物质，从​​本质上讲，它们在所有其他粒子中都表现出独特的特征，这些粒子将允许以最大的约束方式对QCD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，需要在加速器和探测器技术中可能实现实验条件。 Gluex通过采用独特的高强度，极化的光束和密封探测器来解决前者。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常规和混合介体的所有可能衰减模式，同时执行量子数和衰减通道强度测量，以绘制完整的QCD光谱。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）以及介子光谱的意外域。