25th International Workshop on Deep Inelastic Scattering and Related Topics

Model independent measurement of the leptonic kaon decay K+- ->mu+- nu e+ e- and study of the K+ → π+π0e+e− decay by the NA48/2 experiment at CERN

5 Apr 2017, 09:40

25m

West Building Lecture Theatre

WG4) Hadronic and Electroweak Observables WG4 Hadronic and Electroweak Observables

Speakers

Andrea Bizzeti (Universita e INFN, Firenze (IT)) Andrea Bizzeti (U)

Description

The NA48/2 experiment at CERN collected a very large sample of charged kaon decays into multiple final states. From this data sample we have reconstructed about 1500 events of the very rare decay K+- —>mu+- nu e+ e- over almost negligible background in the region with m(e+e-) above 140 MeV, which is of great interest in Chiral Perturbation Theory. We present the m_ee spectrum and a model-independent measurement of the decay rate for this region.

The first observation of about 5000 candidates, with a 5% background contamination, of this rare decay is reported by the NA48/2 experiment at CERN. From the analysis of 1.7 × 10^11 kaon decays collected in 2003–2004, the preliminary branching ratio in the full kinematic region is measured to be (4.22 ± 0.15) × 10^−6. The observed value is in perfect agreement with theoretical predictions based on Chiral Perturbation Theory.

Presentation materials

dis2017_bizzeti_talk1.pdf