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

亚原子物理学寻求在最基本的层面上理解自然及其所有规律，直到它的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，这让我们更加坚信，被称为标准模型的基本模型基本上是对亚原子世界的有效描述，但不一定是一个完整的描述。在标准模型的四种力中，原子核内的强力由一种称为量子色动力学(QCD)的理论来描述。*QCD描述了夸克和胶子相互作用的物理基础，并预测了粒子和共振的虚拟“动物园”。到目前为止，只观察到了无色的“夸克模型”态，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到或被抑制。但QCD预测了更多类型的状态，而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、奇异的物质形式，这些物质的本质是在所有其他粒子中显示出独特的特征，这将使QCD能够以最受约束的方式进行测试。具体地说，混合介子是由胶子量子数与夸克量子数相加而产生的，据预测，杂化介子的子集具有简单夸克模型中不允许的奇异量子数组合。这是一项困难的任务，需要实验条件，而加速器和探测器技术刚刚成为可能。GlueX正在通过使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。我们小组在指导工业发展方面发挥了决定性作用，这些设备现在可以在亚原子、医疗和核安全领域进行商业使用。*GlueX计划通过系统地研究常规介子和混合介子所有可能的衰变模式来绘制完整的QCD谱，同时进行量子数和衰变通道强度测量。我们的团队将继续对低质量介子进行分析，在那些缺乏或没有真实数据的地区。这项研究将提供有争议的(过去低统计能力的实验)以及介子光谱学中未探索的领域的数据。

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.