The NA48/2 experiment at CERN reports the first observation of the K±→π±π0e+e− decay from an exposure of 1.7×10E11 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±π0e+e−)=(4.24±0.14)×10E−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.
First Observation and Study of the K±→π±π0e+e− Decay
Anzivino, G;Imbergamo, E;Piccini, M
2019
Abstract
The NA48/2 experiment at CERN reports the first observation of the K±→π±π0e+e− decay from an exposure of 1.7×10E11 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±π0e+e−)=(4.24±0.14)×10E−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.File in questo prodotto:
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