A sample of 7253 K±→pi±e+e−(γ) decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, which allowed a precise measurement of the decay properties. The branching ratio in the full kinematic range was measured to be BR=(3.11±0.12)×10−7, where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z=(Mee/MK)2, was parameterized according to several models, and, in particular, the slope δ of the linear form factor W(z)=W0(1+δz) was determined to be δ=2.32±0.18. A possible CP violating asymmetry of K+ and K− decay widths was investigated, and a conservative upper limit of 2.1×10−2 at 90% CL was established.

Precise measurement of the K+- --> pi+-e+e- decay

NORTON, Alan Robert;BALDINI, Wander;COTTA RAMUSINO, Angelo;DALPIAZ, Pietro;FIORINI, Massimiliano;GIANOLI, Alberto;PETRUCCI, Ferruccio Carlo;SAVRIE', Mauro;
2009

Abstract

A sample of 7253 K±→pi±e+e−(γ) decay candidates with 1.0% background contamination has been collected by the NA48/2 experiment at the CERN SPS, which allowed a precise measurement of the decay properties. The branching ratio in the full kinematic range was measured to be BR=(3.11±0.12)×10−7, where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z=(Mee/MK)2, was parameterized according to several models, and, in particular, the slope δ of the linear form factor W(z)=W0(1+δz) was determined to be δ=2.32±0.18. A possible CP violating asymmetry of K+ and K− decay widths was investigated, and a conservative upper limit of 2.1×10−2 at 90% CL was established.
2009
J. R., Batley; A. J., Culling; G., Kalmus; C., Lazzeroni; D. J., Munday; M. W., Slater; S. A., Wotton; R., Arcidiacono; G., Bocquet; N., Cabibbo; A., ...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/1379435
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