标题： $B^0\to D_s^{\ast+} D^{\ast-}$介子的部分重建和$D_s^+\toφπ^+$宽度的测量 显示英文标题

标题： Partial Reconstruction of $B^0\to D_s^{\ast+} D^{\ast-}$ Decays and Measurement of the $D_s^+\toφπ^+$ Branching Fraction

摘要： We present preliminary results on the branching fractions $BF(B^0\to D_s^{\ast+} D^{\ast-})$ and $BF(D_s^+\to\phi\pi^+)$, based on a data sample of approximately $124\times10^6$ \BB events collected by the \babar detector at the PEP-II $e^+ e^-$ \B --factory. $BF(B^0\to D_s^{\ast+} D^{\ast-})$是通过选择中性\B 介子衰变到最终态$D_s^{\ast+} D^{\ast-}$的方式测量的，其中只对$D_s^{\ast+}$进行部分重建，在此过程中仅重建了$D^{\ast-}$和来自衰变$D_s^{\ast+} \to D_s^+ \gamma$的软光子。分支比乘积$BF(B^0\to D_s^{\ast+} D^{\ast-}) \cdot BF(D_s^+\to\phi\pi^+)$是通过整个衰变链的完全重建来测量的。 比较这两种测量结果可以提供一种与模型无关的$BF(D_s^+\to\phi\pi^+)$俘获分数的确定。 我们得到以下初步结果： $BF(B^0\to D_s^{\ast+} D^{\ast-}) = (1.85 \pm 0.09 \pm 0.16)%$， $BF(D_s^+\to\phi\pi^+) = (4.71 \pm 0.47 \pm 0.35)%$其中每个测量中的第一个误差是统计误差，第二个是系统误差。 显示英文摘要

摘要： We present preliminary results on the branching fractions $BF(B^0\to D_s^{\ast+} D^{\ast-})$ and $BF(D_s^+\to\phi\pi^+)$, based on a data sample of approximately $124\times10^6$ \BB events collected by the \babar detector at the PEP-II $e^+ e^-$ \B--factory. $BF(B^0\to D_s^{\ast+} D^{\ast-})$ is measured selecting neutral \B meson decays to the final state $D_s^{\ast+} D^{\ast-}$ with partial reconstruction of the $D_s^{\ast+}$, in which only the $D^{\ast-}$ and the soft photons from the decay $D_s^{\ast+} \to D_s^+ \gamma$ are reconstructed. The branching fraction product $BF(B^0\to D_s^{\ast+} D^{\ast-}) \cdot BF(D_s^+\to\phi\pi^+)$ is measured via a complete reconstruction of the whole decay chain. Comparing these two measurements provides a model-independent determination of the $BF(D_s^+\to\phi\pi^+)$ branching fraction. We obtain the following preliminary results: $BF(B^0\to D_s^{\ast+} D^{\ast-}) = (1.85 \pm 0.09 \pm 0.16)%$, $BF(D_s^+\to\phi\pi^+) = (4.71 \pm 0.47 \pm 0.35)%$ where the first error in each measurement is statistical, the second systematic.