Using the full data set of the NA48/2 experiment, the decay K± → π± e+ e- γ is observed for the first time, selecting 120 candidates with 7.3 ± 1.7 estimated background events. With K± → π± πD0 as normalisation channel, the branching ratio is determined in a model-independent way to be Br (K± → π± e+ e- γ, me e γ > 260 MeV / c2) = (1.19 ± 0.12stat ± 0.04syst) × 10-8. This measured value and the spectrum of the e+ e- γ invariant mass allow a comparison with predictions of chiral perturbation theory.
|Original language||English (US)|
|Number of pages||7|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|State||Published - Jan 24 2008|
ASJC Scopus subject areas
- Nuclear and High Energy Physics