X(3872)宽度以及衰变分支比的精确测量

类粲偶素粒子X(3872)自发现至今，对其结构的研究一直是强子物理中的热门课题。因为其多种奇特的性质，理论上对其结构的认知一直存有争论。实验上，尽管已有多个实验对其进行测量，但测量精度仍然很低。北京谱仪（BESIII）实验首次观测到矢量粲偶素通过光子辐射跃迁产生X(3872)的过程，对其结构研究起到积极作用。除此之外，BESIII实验针对X(3872)采集了大统计量的数据，将对其宽度等重要参数做出精确测量。本项目拟采用BESIII获取的数据，对X(3872)的电子对衰变宽度以及衰变分支比进行精确测量。此研究将对相关的理论研究提供实验约束，推动对其结构的认识。

Since the discovery of X(3872), the study of this charmonium-like state has always been a hot topic in hardon physics. Theoretically, there are many different interpretations to its structure. Experimentally, the measurements are still limited due to low statistics. In 2014, BESIII observed the photon transition of Y(4230) to X(3872) for the first time, which is very helpful to the understanding of it structure. In addition, large statistic data dedicated to X(3872) study had been collected at BESIII, which will be used to measure its width and decay fractions at high precision. In this application, a detailed research plan is shown on the study of the width and the decay fractions of X(3872) deploying large statistic data at BESIII. These studies will put strong experimental constraints to the theoretical models.