Title: Inclusive $J/ψ$ Productions at $e^+ e^-$ Colliders Show Chinese title

Title: 包含$J/ψ$产生的$e^+ e^-$对撞机

Abstract: Inclusive $J/\psi$ productions in $e^+ e^-$ annihilation is studied in the framework of NRQCD. We first review the leading-order calculations of the cross sections for $e^+ e^- \to J/\psi c \bar{c}$ and $e^+ e^- \to J/\psi g g$ and find that their ratio is about 1:1.5 at $\sqrt{s}\simeq 10$\gev. This result is in conflict with the current measurements by the Belle Collaboration, which finds that the process $e^+e^- \to J/\psi c\bar{c}$ accounts for about 2/3 of all the prompt $J/\psi$'s. We show that the discrepancy in the total rate as well as in the $J/\psi$ momentum distributions can be resolved by considering a large renormalization $K$ factor ($K\simeq 4$) for the $J/\psi c \bar {c}$ cross section and by taking into account collinear suppression in the end-point energy region of $J/\psi g g$ production. Detailed studies of the model predictions in terms of the density matrix are performed and various momentum and angular distributions are presented as functions of the $K$ factors. These distributions can be used to determine the normalizations of each subprocess provided that the production and decay angular distributions do not alter much by higher order corrections. Show Chinese abstract

Abstract: 在非相对论量子色动力学框架下研究了 $J/\psi$ 在 $e^+ e^-$ 湮灭中的产生。 我们首先回顾了 $e^+ e^- \to J/\psi c \bar{c}$ 和 $e^+ e^- \to J/\psi g g$ 的截面的领先阶计算，并发现它们的比值在 $\sqrt{s}\simeq 10$\gev 处约为 1:1.5。 这个结果与Belle合作组的当前测量结果相矛盾，该测量结果显示过程$e^+e^- \to J/\psi c\bar{c}$约占所有瞬时$J/\psi$的2/3。我们表明，通过考虑$J/\psi c \bar {c}$截面的大重正化$K$因子($K\simeq 4$)，以及考虑到$J/\psi g g$产生末端能量区域中的共线抑制，可以解决总速率以及$J/\psi$动量分布之间的差异。 对密度矩阵的模型预测进行了详细研究，并将各种动量和角分布作为$K$因子的函数进行展示。 这些分布可以在生产与衰变角分布因高阶修正而变化不大的前提下，用于确定每个子过程的归一化。