Final published version
Licence: CC BY: Creative Commons Attribution 4.0 International License
Research output: Contribution to Journal/Magazine › Journal article › peer-review
<mark>Journal publication date</mark> | 10/01/2019 |
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<mark>Journal</mark> | Physics Letters B |
Volume | 788 |
Number of pages | 10 |
Pages (from-to) | 552-561 |
Publication Status | Published |
Early online date | 29/11/18 |
<mark>Original language</mark> | English |
The NA48/2 experiment at CERN reports the first observation of the K ± →π ± π 0 e + e − decay from an exposure of 1.7×10 11 charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR(K ± →π ± π 0 e + e − )=(4.24±0.14)×10 −6 . The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.