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arXiv 1908.01704hep-exhep-phphysics.acc-ph
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LEP光度测量的束-束效应和轻中微子种类数

Beam-beam effects on the luminosity measurement at LEP and the number of light neutrino species

Georgios Voutsinas, Emmanuel Perez, Mogens Dam, Patrick Janot

备注：
Version 4: Fix a typo in the conclusions: $σ_{had} = 41.500 \pm 0.037$ nb, and update Ref [9] (now published)
发表信息：
Physics Letters B 800 (2020) 135068
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摘要：

在$e^+ e^-$碰撞中，由大电荷密度聚束引起的电磁效应修改了实验的光度计系统的有效接受度。因此，这些效应使亮度测量偏离低角度巴巴相互作用$e^+ e^- \to e^+ e^- $的速率。令人惊讶的是，这种偏差的幅度被发现产生约0.1%的LEP实验测量的积分亮度的低估，显着大于报告的实验不确定性。当占，这种影响修改的数量轻中微子物种确定在LEP从测量的强子截面在Z峰。

英文摘要：

In $e^+ e^-$ collisions, electromagnetic effects caused by large charge density bunches modify the effective acceptance of the luminometer system of the experiments. These effects consequently bias the luminosity measurement from the rate of low-angle Bhabha interactions $e^+ e^- \to e^+ e^- $. Surprisingly enough, the magnitude of this bias is found to yield an underestimation of the integrated luminosity measured by the LEP experiments by about 0.1%, significantly larger than the reported experimental uncertainties. When accounted for, this effect modifies the number of light neutrino species determined at LEP from the measurement of the hadronic cross section at the Z peak.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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