We present the first observation of the decay K-S -> pi (+)pi (-)e(+)e(-) based upon the data collected in 1998 by the NA48 experiment at CERN. We have identified a clean sample of 56 events with negligible background contamination. Using K-L -> pi (+)pi (-)pi (0)(D) decays as normalization sample, the branching ratio is measured to be BR(K-S -> pi (+)pi (-)e(+)e(-)) = [4.5 +/- 0.7(stat) +/- 0.4(syst)] x 10(-5). This result is in good agreement with the theoretical expectations from the mechanism of inner bremsstrahlung. (C) 2000 Elsevier Science B.V. All rights reserved.
Observation of the decay K-S -> pi(+)pi(-)e(+)e(-)
MENICHETTI, Ezio;
2000-01-01
Abstract
We present the first observation of the decay K-S -> pi (+)pi (-)e(+)e(-) based upon the data collected in 1998 by the NA48 experiment at CERN. We have identified a clean sample of 56 events with negligible background contamination. Using K-L -> pi (+)pi (-)pi (0)(D) decays as normalization sample, the branching ratio is measured to be BR(K-S -> pi (+)pi (-)e(+)e(-)) = [4.5 +/- 0.7(stat) +/- 0.4(syst)] x 10(-5). This result is in good agreement with the theoretical expectations from the mechanism of inner bremsstrahlung. (C) 2000 Elsevier Science B.V. All rights reserved.
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