Proceedings of 38th International Conference on High Energy Physics — PoS(ICHEP2016)（2017）
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摘要
A measurement of the branching ratio of the rare leptonic kaon decay K ± → µ ± ν µ e + e -is presented using data collected by the NA48/2 experiment in 2003 and 2004.The measurement is performed in the region M ee > 140 MeV/c 2 .In this particular region low energy QCD contributions become important and can be calculated in the framework of Chiral Perturbation Theory (ChPT).From a total number of 1.56 × 10 11 recorded kaon decays, the branching ratio is measured to be B K ± → µ ± ν µ e + e -|M ee > 140 MeV /c 2 = (7.8± 0.2) × 10 -8 .
