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arXiv 1204.0952hep-ex
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用ATLAS探测器测量sqrt(s)= 7 TeV pp碰撞数据中顶夸克对产生的电荷不对称性

Measurement of the charge asymmetry in top quark pair production in pp collision data at sqrt(s) = 7 TeV using the ATLAS detector

Fabian Kohn

摘要:

测量了半轻子衰变道中顶夸克对产生过程中的电荷不对称性。一个数据集对应的积分亮度的1.04反毫微微巴恩,在一个中心的质量能量为7 TeV的ATLAS实验在大型强子对撞机,被使用。在执行一个孤立的轻子,至少有四个喷流和失踪的横向能量的事件的选择后,进行运动学拟合,以重建顶-反顶事件拓扑结构。利用顶夸克和反顶夸克的绝对重构快度之差的微分分布来确定电荷不对称性。一个展开程序被应用到校正探测器接受和分辨率的影响,并获得相应的分布在部分子水平。去折叠后的总电荷不对称性为A_C = -0.018 +/-0.028(stat.)+/- 0.023(系统)与标准模型的预测一致。此外,在绝对重建的快度的顶部和反顶夸克和顶-反顶对的不变质量的差异的同时展开进行。

英文摘要:

A measurement of the charge asymmetry in the production of top quark pairs in the semileptonic decay channel has been performed. A dataset corresponding to an integrated luminosity of 1.04 inverse femtobarn, obtained at a centre-of-mass energy of 7 TeV with the ATLAS experiment at the LHC, was used. After performing a selection of events with one isolated lepton, at least four jets and missing transverse energy, a kinematic fit was performed to reconstruct the top-antitop event topology. The charge asymmetry was determined using the differential distribution of the difference of absolute reconstructed rapidities of the top and antitop quark. An unfolding procedure was applied to correct for detector acceptance and resolution effects and to obtain the corresponding distribution at parton level. The total charge asymmetry after unfolding was measured to be A_C = -0.018 +/- 0.028 (stat.) +/- 0.023 (syst.) in agreement with the Standard Model prediction. In addition, a simultaneous unfolding in the difference of absolute reconstructed rapidities of the top and antitop quark and the invariant mass of the top-antitop pair was performed.

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