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 0 7.3 +/- 11.7 estimated background events. With K -> pi(+/-)pi(0)(D) as normalisation channel, the branching ratio is determined in a model-independent way to be Br(K-+/- -> pi(+/-)e(+)e(-)gamma, m(ee gamma) > 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. (c) 2007 Elsevier B.V. All rights reserved.
First observation and measurement of the decay K-+/-->pi(+/-)e(+)e(-)gamma
COSTANTINI, FLAVIO;GIUDICI, SERGIO;LAMANNA, GIANLUCA;SOZZI, MARCO STANISLAO;
2008-01-01
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 0 7.3 +/- 11.7 estimated background events. With K -> pi(+/-)pi(0)(D) as normalisation channel, the branching ratio is determined in a model-independent way to be Br(K-+/- -> pi(+/-)e(+)e(-)gamma, m(ee gamma) > 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. (c) 2007 Elsevier B.V. All rights reserved.File in questo prodotto:
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