BESIII上正反超子对关联产生及其衰变的实验研究

2019年2月11日北京谱仪III实验圆满完成J/psi粒子数据获取，至此BESIII已经获取了100亿J/psi衰变事例。正负电子对撞产生的矢量J/psi粒子衰变到自旋为1/2的超子对是量子关联过程，正反超子对处于C宇称为-1的状态，故此可以用来研究超子产生中的CP破坏、超子的极化效应。正是因为不同螺旋振幅之间的干涉效应，我们才可以直接测量正反超子产生中的CP破坏，还可以测量正反超子弱衰变中的CP破坏。该测量直接与正反物质不对称，特别是重子数不守恒相关联。在BESIII收集的100亿J/psi事例中，可以重建几百万奇异超子，测量CP破坏的精度可以达到千分之一以下水平，而这一精度可以用来检验标准模型以及新物理模型。 同时，海量正反超子对产生可以允许测量奇异超子的半轻子、辐射、稀有和禁闭的衰变模式，来精确检验标准模型和新物理。

On Feb. 11 2019, BESIII experiment have collected about 10 billion J/psi decays. In the e+e- machine, the system of baryon anti-baryon pair in the J/psi decays is quantum correlated with C= -1. Therefore, we are allowed to measure CP violation in both hyperon pair production and their decays, which is benefit from the transverse polarization of hyperons in the final states. These studies will be connected to the matter-anti-matter asymmetry and even baryon number violation, which are fundamental physics. From 10 billion J/psi decays, we will reconstruct about a few millions of hyperon pairs, which can be used to study the hyperon and anti-hyperon decays simultaneously, thus we can probe the semleptonic, radiative, rare and forbidden decays of hyperons. These precision measurements and searches can be used to test Standard model and probe New Physics.