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オクノ ショウジ
Okuno Shoji 奥野 祥二 所属 神奈川大学 情報学部 システム数理学科 職種 助教 |
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言語種別 | 日本語 |
発行・発表の年月 | 2003/07 |
形態種別 | 学術雑誌 |
査読 | 査読あり |
標題 | Evidence for CP-violating asymmetries in B0→ π+π- decays and constraints on the CKM angle φ2 |
執筆形態 | 共著 |
掲載誌名 | Phys. Rev. D 68, 012001 (2003) (15 pages) |
著者・共著者 | K.Abe, S.Okuno, et al. [BELLE Collaboration], |
概要 | K.Abe, S.Okuno, et al. [BELLE Collaboration], We present an improved measurement of CP-violating asymmetries in B0→ π+π- decays based on a 78 fb-1 data sample collected at the υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We reconstruct one neutral B meson as a B0→ π+π- CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes Aππ = +0.77 ± 0.27(stat) ± 0.08(syst) and Sππ = -1.23± 0.41(stat) -0.07+0.08(syst), where the statistical uncertainties are determined from the Monte Carlo pseudoexperiments. We obtain confidence intervals for CP-violating asymmetry parameters Aππ and Sππ based on a frequentist approach. We rule out the CP-conserving case, Aππ = Sππ = 0, at the 99.93% confidence level. We discuss how these results constrain the value of the Cabibbo-Kobayashi-Maskawa (CKM) angle φ2. |