论文标题
衰减$ \ boldsymbol的分支分数的测量
Measurement of the Branching Fraction of the Decay $\boldsymbol{B^{+}\toπ^{+}π^{-}\ell^{+}ν_\ell}$ in Fully Reconstructed Events at Belle
论文作者
论文摘要
我们介绍了独家$ b^{+} \toπ^{+}π^{ - } \ ell^{+}ν_{\ ell} $ decay，其中$ \ ell $代表电子或muon，假设是电荷conjugsymetry symmetry and lepton and lepton anderality。该分析使用Belle检测器收集的完整$υ（4S）$数据样本，对应于集成光度的711 fb $^{ - 1} $。我们通过在HADRONIC衰变模式下完全重建一个$ b $ erson来选择事件，然后确定其他$ b $ erson的属性。我们使用bined的最大样品拟合在两个泵的不变质量或动量转移平方的箱中提取信号产量。我们测量的总分支分数为$ {{\ cal b}（b^{+} \toπ^{+}π^{ - } \ ell^{+} c {+}ν_{\ ell}）= [22.7^{+1.9} {+1.9} 3.5（\ Mathrm {syst}）] \ Times 10^{ - 5}} $，其中不确定性分别是统计和系统的。该结果是该衰减的第一个报告的测量。
We present an analysis of the exclusive $B^{+}\toπ^{+}π^{-}\ell^{+}ν_{\ell}$ decay, where $\ell$ represents an electron or a muon, with the assumption of charge-conjugation symmetry and lepton universality. The analysis uses the full $Υ(4S)$ data sample collected by the Belle detector, corresponding to 711 fb$^{-1}$ of integrated luminosity. We select the events by fully reconstructing one $B$ meson in hadronic decay modes, subsequently determining the properties of the other $B$ meson. We extract the signal yields using a binned maximum-likelihood fit to the missing-mass squared distribution in bins of the invariant mass of the two pions or the momentum transfer squared. We measure a total branching fraction of ${{\cal B}(B^{+}\to π^{+}π^{-}\ell^{+}ν_{\ell})= [22.7 ^{+1.9}_{-1.6} (\mathrm{stat}) \pm 3.5(\mathrm{syst}) ]\times 10^{-5}}$, where the uncertainties are statistical and systematic, respectively. This result is the first reported measurement of this decay.
