通过J/Ψ→μ^+μ^-确定BESⅢ上J/Ψ总数

Determination of J/Ψ Total Number via J/Ψ→μ^+μ^-at BESⅢ

基于BESⅢ离线软件系统BOSS6.3.4,研究J/Ψ衰变到μ+μ-的事例挑选、探测效率以及本底估计,并用此过程来确定BESⅢ上J/Ψ总数。实验结果显示:用这种方法能得到事例选择效率为55.55%;得到的探测效率与硬件结构相符合;很好地将来自J/Ψ衰变的本底压低,提供了估计QED本底的方法;最后得到蒙特卡罗样本的输入与输出差别为0.08%。以上结果说明该方法适合精确地确定BESⅢ上高统计量的J/Ψ总数。

The events selection,detecting efficiency,and background estimation are studied in the process of J/ψ decaying to μ＋μ-at,based on BES Ⅲ offline software system （BOSS）6. 3. 4 version. It is used to determine J/ψ total number at BES Ⅲ. The results show that the events selection efficiency is 55.55% ,and the detecting efficiency accords with the hardware structure. The background from J/ψ decay is low and a method is provided to estimate the QED background. The difference between the input and output of Monte Carlo sample is 0. 08%. These indicate that this method can be used to precisely determine the total number of J/ψ with high statistical sample at BES Ⅲ.