BESIII上胶球的寻找和轻介子谱的研究

描述强相互作用的量子色动力学理论--QCD在高能下的“渐进自由”性质已被大量实验证实，而低能下的QCD理论尚待进一步的实验检验。有许多重大问题亟待实验回答，如“自然界是否存在由新型强子构成的新的物质形态？低能下如何描述强相互作用系统”等。目前自然界已发现的强子均由2个或3个夸克组成，而QCD理论预言了多于3个夸克的多夸克态、夸克与胶子组成的混杂态和纯胶子组成的胶球等新型强子态的存在。但迄今为止，实验上还未确认新型强子态的存在。J/ψ辐射衰变是丰胶子过程，被公认为是研究和寻找胶球的理想场所。BESIII完成了100亿J/ψ事例样本的获取。我们拟利用这一前所未有的高统计量高质量的J/ψ数据样本，对1-2.5GeV区间的轻介子谱进行系统研究，确认胶球态。研究结果将对我们理解强相互作用的色禁闭，检验和发展QCD理论具有重大的意义。

QCD, a fundamental theory of the strong interactions, is verified at short distances but is not well tested due to the non-perturbative effects at long distances. These effects are basic to the internal structure of hadrons and the spectrum of hadronic states. All the observed hadrons are composite objects with mesons made of a quark-antiquark and baryons made of three quarks, from naïve Quark Model. While QCD describes the interactions of quarks and gluons and thus predicts the existence of other types of hadrons with explicit gluonic degrees of freedom -- glueballs and hybrids, as well as with the number of quarks larger than 3 -- multi-quark states. Glueballs are expected to be copiously produced in J/ψ radiative decays. BESIII just accumulated 10 billion J/ψ events. We plan to study the meson spectroscopy and identify the glueballs in the mass region of 1-2.5 GeV, with BESIII 10 billion J/ψ. The results will be very important in understanding the strong interactions in the strongly coupled non-perturbative regime, and therefore testing and developing QCD.