Charmonium Physics Experiments with the BESIII Detector

胶子相互作用是公认的强相互作用量子色动力学(QCD)理论的核心部分。胶子的自我相互作用应该导致只包含胶子作为成分的状态的存在，胶球。从理论的角度来看，它们是有很好的动机的，例如，晶格计算预测了具有不同量子数和质量的它们的整个光谱。从实验上讲，要将共振的光谱观测确定为胶球要困难得多。这归因于这样一个事实，即强子共振经常在宽度上重叠，并相互混合，使得胶球任务变得模棱两可。这种情况可以通过观察被认为主要涉及胶子的反应中的共振来改善。木炭辐射衰变成轻夸克就属于这一类。在这里观察到新的共振，以及没有观察到像双光子过程这样的胶子贫化反应(见TP Heinsius)，这将是共振胶子特征的一个强烈暗示。然后，来自BESIII的高统计数据允许对胶球衰变进行详细研究，调查它们似乎是目前唯一有希望取得进展的实验方法。通过这种方式，处理到目前为止胶球的推测结构或描述通过中间胶子状态进行的介子强子化的理论可以被检验和完善。为了清楚地区分始终存在的强子背景中的未知共振，需要进行详细的分波分析。要取得最好的结果，就需要在Forschergruppe内部进行密切合作。

The interaction of gluons is a central part of the accepted theory of the strong interaction Quantum Chromo Dynamics (QCD). The self interaction of gluons should lead to the existence of states containing only gluons as constituents, glueballs. From a theoretical point-of-view they are well motivated and e.g. lattice calculations predict a whole spectrum of them with different quantum numbers and masses. Experimentally it is much more difficult to pin down the spectroscopic observation of a resonance as glueball. This is owed to the fact that hadronic resonances often overlap in their widths and mix with each other making the assignment as glueball ambiguous. The situation can be improved by observing resonances in reactions believed to involve mainly gluons. The radiative decay of charmonia into light quarks belongs to this class. The observation of new resonances here and the non-observation in gluon-poor reactions like two-photon processes (see TP Heinsius) would be a strong hint for the gluonic character of the resonance. The high-statistics data from BESIII then allow for a detailed study of glueball decays and investigating them seems currently the only experimental way promising progress. This way, theories dealing with the so far speculative structure of glueballs or describing the hadronization of mesons proceeding via intermediate gluon states could be checked and refined. In order to clearly classify unknown resonances among the always present hadronic background a detailed partial-wave analysis is required. The achievements of the best possible results asks for a close collaboration within the Forschergruppe.