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arXiv · 0711.4313

First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma

2 Collaboration·J. R. Batley
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Abstract

Using the full data set of the NA48/2 experiment, the decay K+- -> pi+- e+ e- gamma is observed for the first time, selecting 120 candidates with 7.3 +- 1.7 estimated background events. With K+- -> pi+- pi0D as normalisation channel, the branching ratio is determined in a model-independent way to be Br(K+- -> pi+- e+ e- gamma, m_eegamma > 260 MeV/c^2) = (1.19 +- 0.12_stat +- 0.04_syst) x 10^-8. This measured value and the spectrum of the e+ e- gamma invariant mass allow a comparison with predictions of Chiral Perturbation Theory.

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2 Collaboration, J. R. Batley. 2007-11-27. First Observation and Measurement of the Decay K+- -> pi+- e+ e- gamma. https://doi.org/10.1016/j.physletb.2007.11.075

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