The ratio R = Gamma(KS -> pi e nu)/Gamma(KS -> pi+pi−) has been measured with a sample of 300 million KS mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DAFNE e+e− collider. KS -> pi e nu events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of KL -> pi e nu decays are used to evaluate signal selection efficiencies. With 49647±316 signal events we measure R = (1.0421 ± 0.0066stat ± 0.0075syst)×10^−3. The combination with our previous measurement gives R = (1.0338 ± 0.0054stat ± 0.0064syst) × 10^−3. From this value we derive the branching fraction B(KS -> pi e nu) = (7.153 ± 0.037stat ± 0.044syst)×10^−4 and f+(0)|Vus| = 0.2170 ± 0.009.
Babusci, D., Berlowski, M., Bloise, C., Bossi, F., Branchini, P., Cao, B., et al. (2023). Measurement of the KS → πeν branching fraction with the KLOE experiment. JOURNAL OF HIGH ENERGY PHYSICS, 2023(2), 0-17 [10.1007/JHEP02(2023)098].
Measurement of the KS → πeν branching fraction with the KLOE experiment
Branchini, P.;Ceradini, F.;Di Cicco, A.;Diociaiuti, E.;Selce, A.
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2023-01-01
Abstract
The ratio R = Gamma(KS -> pi e nu)/Gamma(KS -> pi+pi−) has been measured with a sample of 300 million KS mesons produced in phi -> KLKS decays recorded by the KLOE experiment at the DAFNE e+e− collider. KS -> pi e nu events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of KL -> pi e nu decays are used to evaluate signal selection efficiencies. With 49647±316 signal events we measure R = (1.0421 ± 0.0066stat ± 0.0075syst)×10^−3. The combination with our previous measurement gives R = (1.0338 ± 0.0054stat ± 0.0064syst) × 10^−3. From this value we derive the branching fraction B(KS -> pi e nu) = (7.153 ± 0.037stat ± 0.044syst)×10^−4 and f+(0)|Vus| = 0.2170 ± 0.009.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
