标题： $B \to \D^*$形状因子在半轻子衰变$B^{0}\to D^{*-}\ell^+ ν$中的测量 显示英文标题

标题： Measurement of $B \to \D^*$ Form Factors in the Semileptonic Decay $B^{0}\to D^{*-}\ell^+ ν$

摘要： 我们给出了对\rone 、\rtwo 和\rhosq 的初步测量，这些是用于表征$B\rar D^*\ell\bar\nu_e$形式因子（$A_1$、$V$和$A_2$）的三个参数。 我们使用在PEP-II的\upsfs 共振上积累的$85 \times 10^6$ $B\bar B$对。 在此分析中，我们使用衰变模式$\bar B^0\rar D^{+*}e^-\bar\nu$及其电荷共轭态。 $D^{*+}$在通道$D^{*+}\to D^0\pi^+$中被重建，$D^0$在通道$\dtokpi$中。 我们通过它们的比值（由参数$R_1$和$R_2$确定）和变量$w$中的公共斜率$\rhosq$来参数化\ff （一个与衰变过程中的动量转移相关的量）。这些参数通过无分箱最大似然拟合来确定，拟合的是四个运动学变量（三个衰变角度和$w$）的分布。 结果分别为比值的$R_1= 1.328 \pm 0.055\pm 0.025\pm 0.025$和$R_2=0.920 \pm 0.044\pm 0.020\pm 0.013 $以及斜率的$\rhosq= 0.769\pm 0.039 \pm 0.019\pm 0.032 $。 所述误差分别是数据的统计不确定性、蒙特卡罗样本大小的统计不确定性和系统不确定性。 显示英文摘要

摘要： We present a preliminary measurement of \rone, \rtwo and \rhosq which are the three parameters used to characterize the $B\rar D^*\ell\bar\nu_e$ form factors ($A_1$, $V$, and $A_2$). We use $85 \times 10^6$ $B\bar B$-pairs accumulated on the \upsfs resonance at PEP-II. In this analysis we use the decay mode $\bar B^0\rar D^{+*}e^-\bar\nu$ and its charge conjugate. The $D^{*+}$ is reconstructed in the channel $D^{*+}\to D^0\pi^+$ and the $D^0$ in the channel $\dtokpi$. We parameterize the \ff s in terms of their ratios (determined by the parameters $R_1$ and $R_2$) and the common slope $\rhosq$ in the variable $w$ (a quantity related to the momentum transfer in the decay process). These parameters are determined via an unbinned maximum likelihood fit to the distributions in four kinematic variables (three decay angles and $w$). The results are $R_1= 1.328 \pm 0.055\pm 0.025\pm 0.025$ and $R_2=0.920 \pm 0.044\pm 0.020\pm 0.013 $ for the ratios and $\rhosq= 0.769\pm 0.039 \pm 0.019\pm 0.032 $ for the slope. The stated errors are the statistical uncertainty from the data, statistical uncertainty from the size of the Monte Carlo sample and the systematic uncertainty, respectively.