Study of Hadronic Structure Using Electromagnetic Probes

俄亥俄州大学物理与天文系的丹尼尔教授卡曼和肯尼思·希克斯正在进行的研究是在核物理和粒子物理的交叉领域进行的。 其中一个目标是研究亚原子粒子的产生，这些粒子的组成中至少有一个“奇怪”夸克。 奇怪的夸克比常规的“上”或“下”夸克重，这些夸克构成了原子核中常见的粒子，如质子和中子。 有趣的是，涉及具有“奇异性”的粒子的研究代表了一种研究由非奇异夸克组成的物质的动力学和结构的新方法。 这是通过理解没有奇异性的粒子如何衰变成含有这些奇异夸克的粒子来实现的。 这些实验研究为粒子的夸克结构及其激发态的量子色动力学（QCD）的基础理论提供了更多的信息和约束。 对已知的亚原子粒子集的一个可能的扩展是发现QCD规则允许的“奇异”粒子，但尚未在实验中看到。 特别是，束缚夸克的胶水本身可以携带粒子的一部分自旋量子数，这些粒子被预测存在。 了解这种胶的性质是核物理领域最重要的未解之谜。 卡曼和希克斯在弗吉尼亚州纽波特纽斯的托马斯杰斐逊国家加速器实验室（杰斐逊实验室）进行研究，他们正在寻找奇异粒子的迹象，如果找到的话，将扩展我们对将夸克束缚在一起成为亚原子粒子的强力的知识，并进入我们周围物质的结构。

The research being done by Professors Daniel Carman and Kenneth Hicks of the Department of Physics and Astronomy at Ohio University is conducted in the area of intersection between nuclear and particle physics. One goal is to study the production of subatomic particles having at least one "strange" quark in their makeup. The strange quark is heavier than the conventional "up" or "down" quarks that make up common particles found in the nucleus, like the proton and the neutron. Interestingly, studies involving particles with "strangeness" represent a new way to investigate the dynamics and structure of matter composed of non-strange quarks. Thisis accomplished by understanding how particles without strangeness decay intoparticles containing these strange quarks. These experimental studies provide more information and constraints for the underlying theory of the quark structure of particles and their excited states known as quantum chromodynamics (QCD). One possible extension to the known set of subatomic particles would be the discovery of "exotic" particles which are allowed by the rules of QCD, but not yet seen experimentally. In particular, the glue which binds quarks can itself carry a portion of the spin quantum numbers of a particle, and these particles are predicted to exist. Understanding the nature of this glue is one of the mostimportant unanswered question in the field of nuclear physics. Experiments at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, VA, where Carman and Hicks do their research, are searching for signs of exotic particles, which (if found) will extend our knowledge of the strong force that binds quarks together into subatomic particles and into the very structure of the matter around us.