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D ~+ --> K-pi ~+ e ~+ nu_e衰变通道的分析

Analysis of the D+ --> K- pi+ e+ nu_e decay channel

The BABAR Collaboration, P. del Amo Sanchez

备注：
38 pages, 27 postscript figures, published by Phys. Rev. D
发表信息：
Phys.Rev.D83:072001,2011
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摘要：

利用PEP-Ⅱ正负电子对撞机上BABAR探测器记录的347.5 fb-1数据，分析了D ~+ -> K-pi + e+ nu_e衰变道的244 × 10 ~（^3）个信号事件。这种衰变模式主要由\bar{K}^*（892）^0贡献决定。我们确定\bar{K}^*（892）^0参数：m_{K^*(892)^0} =（895.4 +- 0.2 +- 0.2）MeV/c^{2}，Γ^0_{K^*（892）^0}=（46.5 +- 0.3 +- 0.2）MeV/c^{2}和Blatt-Weisskopf参数$ r_{BW} =2.1 +- 0.5 +- 0.5（GeV/c）^{-1}第一个不确定性来自统计学，第二个来自系统不确定性。我们还测量了q^{2}=0时定义相应强子形状因子的参数（r_{V} = V（0）/ A_{1}（0）=1.463 +-0.017 +-0.031，r_{2} = A_{2}（0）/ A_{1}（0）= 0.801 +- 0.020 +- 0.020）和参数化q^的轴向矢量极质量的值2. A_{1}和A_{2}的变化：m_{A} =（2.63 +- 0.10 +- 0.13）GeV/c^{2}。S波分数等于（5.79 ± 0.16 ± 0.15）%。其它信号分量对应于低于1%的分数。利用D+ --> K-pi + pi+通道作为归一化，我们测量了D+半轻子分支分数：BR（D+ --> K-pi + e+ nu_e）=（4.04 +-0.03 +-0.04 +-0.09）\times 10^{-2}其中第三个不确定度来自外部输入.然后我们得到q^{2}=0时强子形状因子A_1的值：A_{1}（0）= 0.6226 +-0.0056 +-0.0065 +- 0.0074。固定的P波参数，我们测量的相位的S波的几个值的Kpi质量。这些结果证实了在固定目标实验中在小动量转移时Kpi产生所获得的结果。

英文摘要：

Using 347.5 fb-1 of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244*10^3 signal events for the D+ --> K- pi+ e+ nu_e decay channel are analyzed. This decay mode is dominated by the \bar{K}^*(892)^0 contribution. We determine the \bar{K}^*(892)^0 parameters: m_{K^*(892)^0}=(895.4 +- 0.2 +- 0.2) MeV/c^{2}, Γ^0_{K^*(892)^0}=(46.5 +- 0.3 +- 0.2) MeV/c^{2} and the Blatt-Weisskopf parameter $r_{BW}=2.1 +- 0.5 +- 0.5 (GeV/c)^{-1} where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q^{2}=0 (r_{V} = V(0) / A_{1}(0)=1.463 +- 0.017 +- 0.031, r_{2} = A_{2}(0) / A_{1}(0) = 0.801 +- 0.020 +- 0.020) and the value of the axial-vector pole mass parameterizing the q^2 variation of A_{1} and A_{2}: m_{A}=(2.63 +- 0.10 +- 0.13) GeV/c^{2}. The S-wave fraction is equal to (5.79 +- 0.16 +- 0.15)%. Other signal components correspond to fractions below 1%. Using the D+ --> K- pi+ pi+ channel as a normalization, we measure the D+ semileptonic branching fraction: BR(D+ --> K- pi+ e+ nu_e) = (4.04 +- 0.03 +- 0.04 +- 0.09) \times 10^{-2} where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A_1 at q^{2}=0: A_{1}(0) = 0.6226 +- 0.0056 +- 0.0065 +- 0.0074. Fixing the P-wave parameters we measure the phase of the S-wave for several values of the Kpi mass. These results confirm those obtained with Kpi production at small momentum transfer in fixed target experiments.

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