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arXiv 1402.0732hep-ex
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在$BABAR$上研究B介子的重子衰变

Study of baryonic decays of B mesons at $BABAR$

Oliver Gruenberg

摘要:

我们报道了最近对重子$B$衰变$\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}π^{+}π^{-}$、$B^{-}\toΣ_{\rm c}^{++}\bar{p}π^{-}π^{-}$、$\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p}$和$\bar{B}^{0}\to D^{0}Λ\barΛ$的$BABAR$分析。使用的数据样本包含在过程$e^{+}e^{-}\toΥ(4S)\to B\bar{B}$中生成并在SLAC的PEP-II储存环上用$BABAR$检测器收集的$471\times10^{6}\,B\bar{B}$对。我们发现${\cal B}(\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}π^{+}π^{-}) = (12.3\pm0.5_{\rm stat}\pm0.7_{\rm syst}\pm3.2_{\rmΛ_{\rm c}})\times10^{-3}$,${\cal B}(B^{-}\toΣ_{\rm c}^{++}\bar{p}π^{-}π^{-}) = (2.98\pm0.16_{\rm stat}\pm0.15_{\rm syst}\pm0.77_{\rmΛ_{\rm c}})\times10^{-3}$,其中最后的不确定性是由于${\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})$,分别。对于衰减$\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p}$,我们没有看到任何事件,并将上限${\cal B}(\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p})\times \frac{{\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})}{0.050} < 2.8\times10^{-6}$设置为$90\,\%$ CL,其中我们已将${\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})$标准化为世界平均值。有证据表明$\bar{B}^{0}\to D^{0}Λ\barΛ$衰变,我们测量了对应于$3.4σ$显著性的${\cal B}(\bar{B}^{0}\to D^{0}Λ\barΛ) = (9.8^{+2.9}_{-2.6}\,_{\rm stat}\pm1.9_{\rm syst})\times10^{-6}$。

英文摘要:

We report on recent $BABAR$ analyses of the baryonic $B$ decays $\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}π^{+}π^{-}$, $B^{-}\toΣ_{\rm c}^{++}\bar{p}π^{-}π^{-}$, $\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p}$ and $\bar{B}^{0}\to D^{0}Λ\barΛ$. The used data sample contains $471\times10^{6}\,B\bar{B}$ pairs that were generated in the process $e^{+}e^{-}\toΥ(4S)\to B\bar{B}$ and collected with the $BABAR$ detector at the PEP-II storage ring at SLAC. We find ${\cal B}(\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}π^{+}π^{-}) = (12.3\pm0.5_{\rm stat}\pm0.7_{\rm syst}\pm3.2_{\rmΛ_{\rm c}})\times10^{-3}$, ${\cal B}(B^{-}\toΣ_{\rm c}^{++}\bar{p}π^{-}π^{-}) = (2.98\pm0.16_{\rm stat}\pm0.15_{\rm syst}\pm0.77_{\rmΛ_{\rm c}})\times10^{-3}$, where the last uncertainty is due to ${\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})$, respectively. For the decay $\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p}$ we see no events and set an upper limit ${\cal B}(\bar{B}^{0}\toΛ_{\rm c}^{+}\bar{p}p\bar{p})\times \frac{{\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})}{0.050} < 2.8\times10^{-6}$ at $90\,\%$ CL, where we have normalized ${\cal B}(Λ_{\rm c}^{+}\to p K^{-}π^{+})$ to the world average value. There is evidence for the decay $\bar{B}^{0}\to D^{0}Λ\barΛ$ and we measure ${\cal B}(\bar{B}^{0}\to D^{0}Λ\barΛ) = (9.8^{+2.9}_{-2.6}\,_{\rm stat}\pm1.9_{\rm syst})\times10^{-6}$ corresponding to a significance of $3.4σ$.

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