Recent results on Kaon decays from NA48/2

NA48/2 Collaboration

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The first observation of the K± → π±π0e+e rare decay by the NA48/2 experiment at CERN SPS is reported, based on ∼ 2 ×1011 K± decays recorded in 2003-2004. From a sample of 4919 candidates with 4.9% background the branching ratio in the full kinematic region is measured to be BR(K± → π±π0e+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. The CP-violating asymmetry between K+ → π+π0e+e and K → ππ0e+e decay rates has been measured, providing an upper limit |ACP| < 4.82 ×10 2 at 90% CL. The NA48/2 combined measurement of the charged kaon semileptonic form factors, based on 4.4 million K± → π0e±νe and 2.3 million K± → π0µ±νµ events collected in 2004, is presented. This result represents the most precise form factor measurement from a combined Kl ± 3 analysis.

Original languageEnglish (US)
Article number116
JournalProceedings of Science
StatePublished - 2019
Event27th International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS 2019 - Torino, Italy
Duration: Apr 8 2019Apr 12 2019

ASJC Scopus subject areas

  • General


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