Studies of the Microscopic Structure of Hadrons and Hadronic Corrections to Fundamental Properties

匹兹堡小组以各种方式研究亚原子粒子（尺寸小于1毫微微米）的光谱学。 它们有两种，重子（如质子）和介子（如π介子）。 通过测量每个激发态的质量、宽度（有效寿命）和衰变分支到可能的最终状态的分数，大量的信息可用作强相互作用模型的测试。 量子色动力学被强烈认为是合适的理论，但尚未在强子光谱学中得到充分的检验。 实验必须在大型加速器上进行;我们在杰斐逊实验室一直很活跃，在过去几年里，大量的实验已经产生了结果。 我们是CLAS中追踪粒子细节的杰出工作者，并对其中一个关键结果，eta电产生负主要责任。 我们也一直非常积极地构建理论框架，并对数据进行复杂拟合，以确定上述参数。 我们的研究结果预计将导致重大修改粒子数据组的重子属性纲要。 在康奈尔电子储存环的一个特别干净的实验环境中研究介子的新计划已经开始。

The Pittsburgh group studies spectroscopy of subatomic particles (size less than 1 femtometer) in a variety of ways. They come in two kinds, baryons (e.g. proton) and mesons (e.g. pion). By measuring the masses, widths (effectively lifetime)and decay brancing fractions to the possible final states for each excited state, a large body of information is available as a test for models of the strong interaction. Quantum chromodynamics is strongly felt to be the appropriate theory, but has not been adequately tested in hadron spectroscopy. Experiments must be done at large accelerators; we have been active at Jefferson Lab where a large number of experiments have produced results in the last few years. We were prominent workers in the details of tracking particles in CLAS and had primary responsibility for one of the key results, eta electroproduction. We have also been very active in constructing a theoretical framework and doing complex fits to the data in order to determine the parameters discussed above. Our results are expected to cause major modifications to the Particle Data Group compendium of baryon properties. A new program to study mesons in a particularly clean experimental environment at Cornell Electron Storage Ring has been started.