标题： 计算$K^{\pm}\to π^{\pm}π^0e^+e^-$衰变宽度的不同方法 显示英文标题

标题： Different approaches to calculate the $K^{\pm}\to π^{\pm}π^0e^+e^-$ decay width

摘要： 目前由NA48/2合作组正在分析的稀有$K^\pm\to\pi^\pm\pi^0 e^+e^-$衰变被考虑。我们采用了两种理论方法来计算微分衰变宽度——在K介子静止系中，我们使用Cabibbo-Maksimovicz变量，以及在轻子对的质心系中。后者大大简化了计算。已经对这两种方法进行了比较。我们还发现了微分衰变率作为虚光子和双π系统质量的函数的依赖关系。 显示英文摘要

摘要： The rare $K^\pm\to\pi^\pm\pi^0 e^+e^-$ decay, currently under analysis by the NA48/2 Collaboration, is considered. We have performed two theoretical approaches to calculate the differential decay width -- in the kaon rest frame, where we use Cabibbo-Maksimovicz variables, and in the center-of-mass system of the lepton pair. The latter essentially simplifies the computations. A comparison between the two approaches has been performed. We have also found the dependencies of the differential decay rate as a function of the virtual photon and dipion system masses