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B介子B^- -> DK ^-,D -> K^+ π^-衰变的研究

Study of the suppressed B meson decay B^- -> D K^-, D -> K^+ π^-

Belle Collaboration, Y. Horii, K. Trabelsi, H. Yamamoto

摘要:

我们研究了B介子衰变B^- -> DK ^-,然后是D -> K^+ π^-,其中D表示D^0或\bar{D}^0态。这两条衰变路径相互干扰,并提供了CP破坏角θ_3的信息。我们使用的数据样本包含657 x 10^6个B \bar{B}对,它们是在KEKB非对称能量e^+e^-储存环上用Belle探测器以双(4S)共振记录的。我们没有发现B^- -> D K^-,D -> K^+ π^-模式的显著证据,并设定了r_B < 0.19的上限,其中r_B是振幅比的大小|A(B^- -> \bar{D}^0 K^-)/A(B^- -> D^0 K^-)|.我们还分析了衰变B^- -> D π^-,D -> K^+ π^-作为参考,我们观察到一个6.6σ显著性的信号,并测量了电荷不对称性A_{Dπ}为-0.02 ^{+0.15}_{-0.16}(stat)\pm 0.04(syst)。此外,测得B(B^- -> D^0 K^-)/B(B^- -> D^0 π^-)的比值为[6.77 \pm 0.23(stat)\pm 0.30(syst)] x 10^{-2}。

英文摘要:

We report a study of the suppressed B meson decay B^- -> D K^- followed by D -> K^+ π^-, where D indicates a D^0 or \bar{D}^0 state. The two decay paths interfere and provide information on the CP-violating angle ϕ_3. We use a data sample containing 657 x 10^6 B\bar{B} pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- storage ring. We do not find significant evidence for the mode B^- -> D K^-, D -> K^+ π^-, and set an upper limit of r_B < 0.19, where r_B is the magnitude of the ratio of amplitudes |A(B^- -> \bar{D}^0 K^-)/A(B^- -> D^0 K^-)|. The decay B^- -> D π^-, D -> K^+ π^- is also analyzed as a reference, for which we observe a signal with 6.6σsignificance, and measure the charge asymmetry A_{Dπ} to be -0.02^{+0.15}_{-0.16}(stat) \pm 0.04(syst). In addition, the ratio B(B^- -> D^0 K^-)/B(B^- -> D^0 π^-) is measured to be [6.77 \pm 0.23(stat) \pm 0.30(syst)] x 10^{-2}.

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