Discovering Exotics at Jefferson Lab

在杰斐逊实验室发现异国情调

• 批准号: 2276386
• 金额: --
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2276386
• 关键词: Discovering; Exotics; Jefferson; Lab

The Hadron and Nuclear Physics group at the University of York is looking for a bright and enthusiastic PhD student todiscover exotic particles at Jefferson Laboratory utilizing intense electron beam and CLAS detector.The fundamental theory thought to describe the strong interaction is Quantum Chromodynamics (QCD). QCD permits a large variety of bound states of quarks. The simplest and best-established configurations are mesons (quark-anti-quark systems) and baryons (3 quark systems). The field is currently undergoing rapid change with claims of tetraquarks, pentaquarks, hexaquarks and hadronic molecules only recently starting to reveal themselves. The advance has been made possible through exploiting cutting-edge particle beams at the frontiers of intensity, coupled for the first time with large acceptance particle detectors. The field has attracted very significant public interest and has high scientific impact. Stories about discoveries of new exotic particles attract significant media attention.Our group is leading exciting studies which are revealing six-quark states - hexaquarks [PRL 1,2,3,4]. We exploit the uniquely clean and controlled production environment accessible through photo- and electro-induced reactions. Proving the exotic nature of a new particle is a challenging task for the majority of the cases. However hexaquarks, where baryon number B=2 are easily identifiable. Our group was involved in a recent discovery of a first non-trivial hexaquark, the d* (2380), having quark content uuuddd. A large fraction of our current activities are now devoted to this discovery: we have recently shown that the d*(2380) may form copiously within neutron stars influencing fundamental properties [PLB] and also be produced significantly in early Universe.Like any other particles, the d*(2380) does not appear alone, but as a part of an SU(3) multiplet. In the d*'s case it is antidecuplet, so we expect 9 more particles with the same spin-parity (JP = 3+) but different strangeness to be discovered. The next candidate for the discovery would be ds - a particle with a quark content uuudds. This particle can be produced in large quantities at the JLab facility and detected by the high acceptance CLAS12 detector apparatus. After the energy and the luminosity upgrade of the JLab one can collect adequate statistics within few weeks of data taking. The first CLAS beam time with a deuteron target has been just started. For a PhD student it would be a golden opportunity to start the project with the data taking and complete it with an important discovery paper.

约克大学的强子和核物理小组正在寻找一位聪明而热情的博士生，以利用强电子束和 CLAS 探测器在杰斐逊实验室发现奇异粒子。描述强相互作用的基本理论是量子色动力学 (QCD)。 QCD 允许夸克存在多种束缚态。最简单和最完善的配置是介子（夸克-反夸克系统）和重子（3夸克系统）。该领域目前正在经历快速变化，四夸克、五夸克、六夸克和强子分子的主张直到最近才开始显现出来。这一进步是通过利用强度前沿的尖端粒子束并首次与大接收粒子探测器相结合而实现的。该领域引起了公众的极大兴趣并具有很高的科学影响力。有关新奇特粒子的发现的故事引起了媒体的广泛关注。我们的小组正在领导令人兴奋的研究，这些研究揭示了六夸克态 - 六夸克 [PRL 1,2,3,4]。我们利用通过光诱导反应和电诱导反应实现的独特清洁和受控生产环境。对于大多数情况来说，证明新粒子的奇异性质是一项具有挑战性的任务。然而，重子数 B=2 的六夸克很容易识别。我们小组最近发现了第一个非平凡的六夸克，即 d* (2380)，其夸克含量为 uuuddd。我们目前的大部分活动都致力于这一发现：我们最近表明，d*(2380) 可能在中子星内大量形成，影响基本特性 [PLB]，并且在早期宇宙中也会大量产生。像任何其他粒子一样，d*(2380) 不会单独出现，而是作为 SU(3) 多重态的一部分出现。在 d* 的情况下，它是反十重态，因此我们预计还会发现 9 个具有相同自旋宇称 (JP = 3+) 但具有不同奇异性的粒子。该发现的下一个候选者将是 ds——一种夸克含量为 uuudds 的粒子。这种颗粒可以在 JLab 设施中大量生产，并由高可接受性 CLAS12 检测器设备检测到。 JLab 的能量和光度升级后，人们可以在数据采集后的几周内收集足够的统计数据。第一个使用氘核目标的 CLAS 束流时间刚刚开始。对于博士生来说，这将是一个绝佳的机会，可以通过数据采集来启动该项目，并通过一篇重要的发现论文来完成该项目。