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arXiv 1005.2302hep-ex
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在Belle观测到B+ -> Dbar*0 tau+ nu_tau和B+ -> Dbar ^0 tau+ nu_tau的证据

Observation of B+ -> Dbar*0 tau+ nu_tau and Evidence for B+ -> Dbar^0 tau+ nu_tau at Belle

A. Bozek, M. Rozanska et al.

摘要:

我们在KEKB非对称能量e+e-对撞机上用Belle探测器收集了657 x 10^6个BBbar对的数据样本,并给出了B+ -> Dbar * 0 tau + nu_tau和B+ -> Dbar ^0 tau+ nu_tau衰变的测量结果。我们发现446^{+58}_{-56}个衰变B+ -> Dbar*0 τ + nu_tau事件,其显著性为8.1标准差,146^{+42}_{-41}个衰变B+ -> Dbar 0 τ + nu_tau事件,其显著性为3.5标准差。后一个信号提供了这种衰变模式的第一个证据。测得的支化分数为B(B+ -> Dbar*0 tau+ nu_tau)=(2.12^{+0.28}-0.27}(stat)+-0.29(syst))%和B(B+ -> Dbar 0 tau+ nu_tau)=(0.77 +-0.22(stat)+-0.12(syst))%。

英文摘要:

We present measurements of B+ -> Dbar*0 tau+ nu_tau and B+ -> Dbar^0 tau+ nu_tau decays in a data sample of 657 x 10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. We find 446^{+58}_{-56} events of the decay B+ -> Dbar*0 tau+ nu_tau with a significance of 8.1 standard deviations, and 146^{+42}_{-41} events of the decay B+ -> Dbar0 tau+ nu_tau with a significance of 3.5 standard deviations. The latter signal provides the first evidence for this decay mode. The measured branching fractions are B(B+ -> Dbar*0 tau+ nu_tau)=(2.12^{+0.28}_{-0.27} (stat) +- 0.29 (syst)) % and B(B+ -> Dbar0 tau+ nu_tau)=(0.77 +- 0.22 (stat) +- 0.12 (syst)) %.

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