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arXiv 1207.2690hep-ex
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B到X_s γ光子能谱、分支分数和直接CP非对称性A_{CP}（B到X_{s+d} γ）的精确测量

Precision Measurement of the B to X_s γPhoton Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A_{CP}(B to X_{s+d}γ

The BaBar Collaboration

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8 pages, 2 figures, submitted to PRL
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摘要：

利用SLAC的\babar \实验收集的$(382.8 \pm 4.2) \times 10^6$ $Υ(4S) \to B\overli\ ne{B}$衰变数据样本，研究了$B$介子$B \to X_{s} γ$ + $B \to X_{d} γ$的电磁辐射衰变的光子谱.该光谱用于提取$E_γ>1.8 \gev$的支化分数${\cal B}(B \to X_{s} γ)=(3.21 \pm 0.33)\times 10^{-4}$和直接CP不对称性$A_{CP}(B \to X_{s+d} γ)=0.057 \pm 0.063$。在$B$介子静止系中，利用探测器分辨率和多普勒拖尾效应测量光子能谱。

英文摘要：

The photon spectrum in the inclusive electromagnetic radiative decays of the $B$ meson, $B \to X_{s} γ$ plus $B \to X_{d} γ$, is studied using a data sample of $(382.8 \pm 4.2) \times 10^6$ $Υ(4S) \to B\overli\ ne{B}$ decays collected by the \babar\ experiment at SLAC. The spectrum is used to extract the branching fraction ${\cal B}(B \to X_{s} γ)=(3.21 \pm 0.33)\times 10^{-4}$ for $E_γ>1.8 \gev$ and the direct CP asymmetry $A_{CP}(B \to X_{s+d} γ)=0.057 \pm 0.063$. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the $B$ meson rest frame.

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