The NA48/2 experiment at CERN reports the first observation of the K ±→π ±π 0e +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 0e +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.
|Number of pages||10|
|Journal||Physics Letters B|
|Early online date||29 Nov 2018|
|Publication status||Published - 10 Jan 2019|
ASJC Scopus subject areas
- Nuclear and High Energy Physics