Precise measurement of the K±→π±e+e− decay
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Colleges, School and Institutes
A sample of 7253 K±→π±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=2(Mee/MK), 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.
|Number of pages||9|
|Journal||Physics Letters B|
|Publication status||Published - 29 Jun 2009|