标题： 关于质量粒子引力场对称性的注记 显示英文标题

标题： A Note on the Symmetries of the Gravitational Field of a Massless Particle

摘要： 显示通过将施瓦茨希尔德度规加速到光速获得的无质量粒子的度规，具有四个与$E(2)\times \RR$对称性群对应的Killing向量。 这与基于平空间运动学的预期一致，但与文献中以前的陈述\cite{Schueck}相矛盾。 此外，它还超越了如\cite{JEK}中所述的引力pp波的一般Jordan-Ehlers-Kundt-(JEK)分类。 显示英文摘要

摘要： It is shown that the metric of a massless particle obtained from boosting the Schwarzschild metric to the velocity of light, has four Killing vectors corresponding to an $E(2)\times \RR$ symmetry-group. This is in agreement with the expectations based on flat-space kinematics but is in contrast to previous statements in the literature \cite{Schueck}. Moreover, it also goes beyond the general Jordan-Ehlers-Kundt-(JEK)-classification of gravitational pp-waves as given in \cite{JEK}.