A MODEL INDEPENDENT ANALYSIS OF LEP AND SLD DATA ON Z-DECAYS ; IS THE STANDARD MODEL CONFIRMED ?
A MODEL INDEPENDENT ANALYSIS OF LEP AND SLD DATA ON Z-DECAYS ; IS THE STANDARD MODEL CONFIRMED ?
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Z 衰变 LEP 和 SLD 数据的模型独立分析；
DOI：
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发表时间：
1998
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通讯作者：
J. Field
中科院分区：
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作者：
J. Field
对Z衰变的LEP和SLD数据进行了与模型无关的分析。仅在很弱的理论假设下，我们就提取了轻子、c夸克和B夸克的有效矢量耦合和轴矢量耦合。虽然轻子和c夸克耦合与标准模型的预测吻合得很好，但B夸克的耦合却显示出超过三个标准差的偏差。这种效应主要表现在右手B夸克耦合中，左手夸克耦合与标准模型的预测一致（在2σ水平上）。所有测量的有效耦合的观测偏差是来自轻子普适性和标准模型的统计涨落的概率估计为0.9%。轻子和B夸克耦合的偏差单独是涨落的概率估计为0.18%。一个彻底的讨论是由不同的测量有助于平均值Al和Ab用于提取的B夸克耦合的内部一致性，以及可能的系统误差的来源，可能没有，迄今为止，已被考虑在内。从平均值中排除τ -极化测量（显示内部不一致），将提取的B夸克耦合与标准模型预测的偏差增加到4个标准差水平。PACS 13.10.+ q，13.15.Jr，13.38.+ c，14.80.Er，14.80.Gt
A model independent analysis has been performed on the LEP and SLD data on Z decays. Using only very weak theoretical assumptions, the effective vector and axial-vector couplings of leptons, c quarks and b quarks have been extracted. Although the lepton and c quark couplings agree well with Standard Model predictions, those of the b quark show deviations of more than three standard deviations. The effect is mainly in the right-handed b quark coupling, the left-handed coupling being consistent (at the 2σ level) with the Standard Model prediction. The probability that the observed deviations of all the measured effective couplings are statistical fluctuations from lepton universality and the Standard Model is estimated to be 0.9%. The estimated probability that the deviations in the leptonic and b quark couplings alone are a fluctuation is 0.18%. A thorough discussion is made of the internal consistency of the different measurements contributing to the average values Al and Ab used to extract the b quark couplings, as well as possible sources of systematic error that may not, hitherto, have been taken into account. Excluding τ -polarisation measurements, which show internal inconsistencies, from the averages increases the deviations of the extracted b quark couplings from the Standard Model predictions to the four standard deviation level. PACS 13.10.+q, 13.15.Jr, 13.38.+c, 14.80.Er, 14.80.Gt