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arXiv 1111.5023hep-exhep-ph
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在CDF的D0 --> pi+ pi-和D0 --> K+K-衰变中测量CP -破坏的不对称性

Measurement of CP--violating asymmetries in D0 --> pi+ pi- and D0 --> K+K- decays at CDF

CDF Collaboration, T. Aaltonen

摘要:

本文报道了在费米实验室升级后的对撞机探测器收集的对应于5.9 fb-1积分亮度的数据样本中重建的Cabibbo抑制的D 0-> pi+ pi-和D 0-> K+K-衰变中CP破坏不对称性(Acp)的测量结果。我们利用强衰变D ~*+ --> D ~ 0 π ~+来鉴别粲介子产生时的味,并利用CP守恒的强c-cbar对产生.高统计样本的Cabibbo青睐的D 0--> K- p+衰变与D* 标签和没有被用来校正仪器的影响,并显着降低系统的不确定性。我们测得Acp(D 0--> pi+ pi-)=(+0.22 +-0.24(stat)+-0.11(syst))%和Acp(D 0 --> K+ K-)=(-0.24 +-0.22(stat)+-0.09(syst))%,与CP守恒一致。这是迄今为止单次实验中最精确的测定。在D_0--> π + π-和D_0--> K+K-衰变中直接CP破坏可忽略的假设下,结果给出了D_0混合中CP破坏不对称性的上限,|Acp^{ind}(D0)|在90%置信水平下< 0.13%。

英文摘要:

We report on a measurement of CP-violating asymmetries (Acp) in the Cabibbo-suppressed D0 --> pi+ pi- and D0 --> K+K- decays reconstructed in a data sample corresponding to 5.9 fb-1 of integrated luminosity collected by the upgraded Collider Detector at Fermilab. We use the strong decay D*+ --> D0 pi+ to identify the flavor of the charmed meson at production and exploit CP-conserving strong c-cbar pair-production in p-pbar collisions. High-statistics samples of Cabibbo-favored D0 --> K- p+ decays with and without a D* tag are used to correct for instrumental effects and significantly reduce systematic uncertainties. We measure Acp(D0 --> pi+ pi-) = (+0.22 +- 0.24 (stat) +- 0.11 (syst))% and Acp(D 0 --> K+ K-) = (-0.24 +- 0.22 (stat) +- 0.09 (syst))%, in agreement with CP conservation. These are the most precise determinations from a single experiment to date. Under the assumption of negligible direct CP violation in D0 --> pi+ pi- and D0 --> K+K- decays, the results provide an upper limit to the CP-violating asymmetry in D0 mixing, |Acp^{ind}(D0)|< 0.13% at the 90% confidence level.

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