arXiv 1810.054872018-10-12hep-ex

顶夸克物理在第一CLIC阶段

Top-quark physics at the first CLIC stage

Aleksander Filip Zarnecki

备注：: 4 pages, 3 figures, to be submitted to proceedings of ICHEP'2018, presented on behalf of the CLICdp Collaboration

摘要：

紧凑型直线对撞机（CLIC）是未来电子-正电子对撞机的成熟选择，其质心能量高达3 TeV。CLIC将以分阶段的方式建造和运行，目前假定三个质心能量为380 GeV，1.5 TeV和3 TeV。本文讨论了在CLIC的第一阶段的顶夸克性质的精确测量的前景，基于详细的模拟研究，考虑到光度谱和光束诱导的背景，基于Geant 4的全探测器模拟，基于粒子流方法与PandoraPFA的最终状态重建，射流聚类与VLC算法在FastJet包中实现，和LcfiPlus的味道标记。基于围绕顶夸克对产生阈值的专用质心能量扫描，可以以理论上明确定义的方式以约50 MeV的精度确定顶夸克质量。这种扫描对顶夸克宽度和汤川耦合也很敏感。在CLIC第一阶段提取顶夸克质量的其他方法使用ISR光子或直接重建顶夸克。在380 GeV的微分顶夸克对生产截面的精确测量，对于不同的电子束极化，允许研究顶夸克耦合到电弱规范玻色子敏感的新物理质量尺度超过10 TeV。产生的大量顶夸克对也允许竞争性搜索变味中性流（FCNC）顶夸克衰变与最终状态的粲夸克。对于$t\rightarrow ch$、$t\rightarrow cγ$和$t\rightarrow c E_{miss}$通道，列出了CLIC第一阶段收集的500 fb $^{-1}$的预期排除限值，对于BR（$t\rightarrow cγ$），该限值可降至$4.7 \cdot 10^{-5}$。

英文摘要：

The Compact Linear Collider (CLIC) is a mature option for a future electron-positron collider operating at centre-of-mass energies of up to 3 TeV. CLIC will be built and operated in a staged approach with three centre-of-mass energies currently assumed to be 380 GeV, 1.5 TeV and 3 TeV. This contribution discusses the prospects for precision measurements of top-quark properties at the first stage of CLIC, based on detailed simulation studies, taking into account luminosity spectra and beam induced backgrounds, full detector simulation based on Geant4, final state reconstruction based on particle flow approach with PandoraPFA, jet clustering with the VLC algorithm as implemented in the FastJet package, and flavour tagging with LcfiPlus. Based on a dedicated centre-of-mass energy scan around the top-quark pair production threshold, the top-quark mass can be determined with a precision of about 50 MeV in a theoretically well-defined manner. This scan is also sensitive to the top-quark width and Yukawa coupling. Other approaches to extract the top-quark mass at the first stage of CLIC make use of ISR photons or the direct reconstruction of the top quarks. Precise measurements of the differential top-quark pair production cross sections at 380 GeV, for different electron beam polarisations, allow the study of top-quark couplings to electroweak gauge bosons sensitive to new physics mass scales beyond 10 TeV. The large number of top-quark pairs produced also allows competitive searches for Flavour Changing Neutral Current (FCNC) top-quark decays with charm quarks in the final state. Exclusion limits expected for 500 fb$^{-1}$ collected at the first stage of CLIC are presented for $t\rightarrow ch$, $t\rightarrow cγ$ and $t\rightarrow c E_{miss}$ channels, reaching down to $4.7 \cdot 10^{-5}$ for BR($t\rightarrow cγ$).

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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英文摘要：

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