J/ψ衰变过程的矩分析和两种坐标系的比较

Moment Analysis of J/ψ Decay Processes and Comparison of Results in Two Frames

讨论了实验室坐标系和螺旋度坐标系中不极化电子－正电子对撞产生Ｊ／ψ粒子的密度矩阵，指出，产生的Ｊ／ψ粒子只有螺旋度±１的分量对过程有贡献的结论是有条件的，且仅适用于实验室坐标系；在两种坐标系中应用矩分析方法时，将得到相同数目的矩，而且矩的表达式之间存在一个十分简单的关系式。

The density matrices of J/ψ produced in the non-polarized e+-e- collisions inboth experimental laboratory and helicity frame are discussed. The results show that rthe conclkusion for only J/ψwith the helicity ±1 having contributions to the procssis correct only in the experimental laboratory frame under some conditions. The number of the moments is the same and there is a simple relation between the momentsin the two frames.