Research and Education with GlueX

托马斯·杰斐逊国家加速器设施(杰斐逊实验室)的GlueX实验正在寻找一种名为混合介子的新粒子的证据，这种粒子预计将基于粒子物理的标准模型而存在。现有的最好的混合介子理论计算预测，在1.8到2.5GeV/c之间的质量范围内应该存在27个这样的介子。GlueX已经建立起来，以极高的灵敏度研究这个完整的质量区域，使用高强度的偏振光子束和能够从这些新粒子的衰变产物的动量分布中识别这些新粒子的最先进的探测器。康涅狄格大学的GlueX小组由PI、一名博士生和两名本科生研究员组成。该团队负责生产钻石靶材，从杰斐逊实验室加速器中加速的电子产生极化高能光子束，确保它们满足晶体质量和平坦度方面的严格要求。该小组还建造并维护了用于测量光子束能量的标记“显微镜”探测器。根据这笔拨款获得的支持使康涅狄格州大学的团队能够在未来三年前往纽波特纽斯支持GlueX实验的操作，并致力于GlueX数据的分析。过去20年来，对混合介子的实验性搜索大多一无所获，除了一两个杰出的候选者。一个看似合理的原因是，之前的搜索集中在错误的质量区域，而较早的模型计算表明，最轻的混合粒子的质量可能小于1.5GeV。在过去的十年里，出现了更好的预测，指出最轻的3混合NONET的质量区域更高，为1.8-2.5GeV。GlueX的建立是为了研究这个全质量区域，具有极好的质量分辨率和高统计量，在由9GeV偏振光子产生的照片中。在过去的三年中，GlueX已经完成了调试和初始物理数据获取阶段。在接下来的三年里，该实验将收集完成其初级物理任务所需的完整数据集的主要部分，并将完成对感兴趣质量范围内的共振情况的初步调查，最初专注于少数有利于混合衰变的排他性最终状态。康涅狄格州大学团队通过为GlueX编写和维护物理模拟包，管理物理模拟的共享计算机资源，以及参与共享数据分析工作来支持分析工作。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The GlueX experiment at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) searches for evidence of a new class of particles called hybrid mesons, which are expected to exist based on the Standard Model of particle physics. The best existing theory calculations for hybrid mesons predicts that 27 such mesons should exist within the mass between 1.8 and 2.5 GeV/c. GlueX has been built to study this full mass region with excellent sensitivity, using a high-intensity polarized photon beam and a state-of-the-art detector capable of identifying these new particles from the momentum distributions of their decay products. The GlueX group at University of Connecticut consists of the PI, one PhD student, and two undergraduate student researchers. This team is responsible for producing the diamond targets that generate the polarized high-energy photon beam from electrons accelerated in the Jefferson Lab accelerator, making sure they meet the stringent requirements in terms of crystal quality and flatness. The group also constructed and maintains the tagging "microscope" detector that is used to measure the photon beam energy. Support received under this grant enables the UConn team to travel to Newport News to support the operation of the GlueX experiment over the next three years, and to work on the analysis of GlueX data.Experimental searches for hybrid mesons over the past 20 years have mostly come up empty, except for one or two outstanding candidates. One plausible reason for this is that prior searches have focused on the wrong mass region, guided by older model calculations which indicated that the masses of the lightest hybrids might be less than 1.5 GeV. Within the past decade, improved predictions have emerged, pointing to a higher mass region 1.8 - 2.5 GeV for the lightest 3 hybrid nonets. GlueX has been built to study this full mass region, with excellent mass resolution and high statistics, in photo production by polarized 9 GeV photons. During the past three years, GlueX has completed commissioning and initial physics data-taking phases. Over the next three years, the experiment will collect a major part of the full dataset required to complete its primary physics mission, and will complete an initial survey of the resonance landscape over the mass range of interest, focusing initially on a small number of exclusive final states that are favored for hybrid decays. The UConn group supports the analysis effort by authoring and maintaining the physics simulation package for GlueX, managing shared computer resources for physics simulation, and participating in the shared data analysis effort.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.