A sample of 7253 K(+/-) -> pi(+/-)e(+)e(-)(gamma) 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) x 10(-7), where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z = (M(ee)/M(K))(2) was parameterized according to several models, and, in particular, the slope delta of the linear form factor W(z) = W(0)(1 + delta z) was determined to be delta = 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 X 10(-2) at 90% CL was established.

Precise measurement of the K±->π±e+e− decay

MARTELLI, FILIPPO;VELTRI, MICHELE;
2009-01-01

Abstract

A sample of 7253 K(+/-) -> pi(+/-)e(+)e(-)(gamma) 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) x 10(-7), where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z = (M(ee)/M(K))(2) was parameterized according to several models, and, in particular, the slope delta of the linear form factor W(z) = W(0)(1 + delta z) was determined to be delta = 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 X 10(-2) at 90% CL was established.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2302076
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