Study of light mesons in two-photon interaction

为了理解强相互作用的本质，人们需要解决一个难题，为什么发现的共振不能像标准夸克模型那样全部被描述为介子。事实上，强相互作用理论预言了不同类型的束缚态，如杂化体、四夸克和胶球。这些还没有被唯一地确定，需要对不同的产生机制进行研究，以区分具有相同量子数的粒子。本项目研究了双光子相互作用中产生的轻介子。这些数据来自高统计量的BESIII实验。特别地，在耦合通道分波分析中分析了具有π、η、a和f的量子数的状态。该项目的重点是它们衰变成π介子，奇异粒子和η粒子。它们最有可能取得新的成果。与其他方案的比较将阐明束缚态和强相互作用的性质。

To understand the nature of strong interaction one needs to solve the puzzle why the discovered resonances cannot all be described as mesons like in the standard quark model. In fact the theory of strong interaction predicts different types of bound states like hybrids, tetraquarks and glueballs. These are not yet uniquely identified and a study of different productions mechanisms is required to distinguish particles with the same quantum numbers. In this project the light mesons produced in two-photon interaction are studied. The data are obtained from the high-statistics BESIII experiment. In particular states with quantum numbers of the pi, eta, a and f are analyzed in a coupled channel partial wave analysis. The project focuses on their decays into pions, strange and eta particles. These have the highest potential to obtain new results. Comparisons with the other projects will shed light on the nature of the bound states and the strong interaction.