6 Study of the branching ratio and charge asymmetry for the decay K S → πeν with the KLOE detector
نویسندگان
چکیده
Among some 400 million KSKL pairs produced in e +e− annihilations at DAΦNE, ∼ 6500 each of KS→π +e−ν̄ and KS→π −e+ν decays have been observed with the KLOE detector. From these, the ratio Γ(KS → πeν)/Γ(KS → π +π−) = (10.19 ± 0.13) × 10−4 is obtained, improving the accuracy on BR(KS → πeν) by a factor of four and providing the most precise test of the ∆S=∆Q rule. From the partial width Γ(KS → πeν), a value for f K + (0)×Vus is obtained that is in agreement with unitarity of the quark-mixing matrix. The lepton charge asymmetry AS = (1.5±9.6stat±2.9syst)×10 −3 is compatible with the requirements of CPT invariance. The form-factor slope agrees with recent results from semileptonic KL and K + decays. These are the first measurements of the charge asymmetry and form-factor slope for semileptonic KS decays.
منابع مشابه
/ 06 01 02 6 v 1 1 3 Ja n 20 06 Measurement of the branching fraction and charge asymmetry for the decay K S → πeν with the KLOE detector
Among some 400 million KSKL pairs produced in e +e− annihilations at DAΦNE, ∼ 6500 each of KS→π +e−ν̄ and KS→π −e+ν decays have been observed with the KLOE detector. From these, BR(KS → πeν) = (7.046 ± 0.091) × 10 −4 is obtained, improving the accuracy on the BR by a factor of four and providing the most precise test of the ∆S = ∆Q rule. From the partial width Γ(KS → πeν), f K + × Vus = 0.2162 ±...
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