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arXiv 0807.4977hep-ex
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B0 -> rho0rho0衰变中分支分数、极化和CP不对称性的测量,以及对CKM角α的影响

Measurement of the Branching Fraction, Polarization, and CP Asymmetries in B0->rho0rho0 Decay, and Implications for the CKM Angle alpha

The BaBar Collaboration, B. Aubert

摘要:

我们研究了位于斯坦福直线加速器中心(SLAC)的PEP-II非对称能量e+e对撞机上的BABAR探测器收集的465*10^6 Upplane(4S)->BBbar事件样本中的B 0-> rho 0 rho 0衰变。我们测量了分支分数B =(0.92 +/- 0.32 +/- 0.14)*10^{-6}和纵向极化分数f_L = 0.75^{+0.11}_{-0.14} +/- 0.04,其中第一个不确定度是统计的,第二个是系统的。B 0-> rho 0 rho 0信号的证据具有3.1标准差的显著性,包括系统不确定性。我们研究了衰变中的纵分量对本征时间的依赖性,并测量了CP破坏系数S^{00}_L =(0.3 +/-0.7 +/-0.2)和C^{00}_L =(0.2 +/-0.8 +/-0.3).我们研究了这些结果对幺正三角角α的影响。

英文摘要:

We study B0->rho0rho0 decays in a sample of 465*10^6 Upsilon (4S)->BBbar events collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider located at the Stanford Linear Accelerator Center (SLAC). We measure the branching fraction B = (0.92 +/- 0.32 +/- 0.14)*10^{-6} and longitudinal polarization fraction f_L = 0.75^{+0.11}_{-0.14} +/- 0.04, where the first uncertainty is statistical and the second is systematic. The evidence for the B0->rho0rho0 signal has a significance of 3.1 standard deviations, including systematic uncertainties. We investigate the proper-time dependence of the longitudinal component in the decay and measure the CP-violating coefficients S^{00}_L = (0.3 +/- 0.7 +/- 0.2) and C^{00}_L = (0.2 +/- 0.8 +/- 0.3). We study the implication of these results for the unitarity triangle angle alpha.

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