Observation of four-top-quark production in the multilepton final state with the ATLAS detector
Observation of four-top-quark production in the multilepton final state with the ATLAS detector
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DOI：
10.1140/epjc/s10052-023-11573-0
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
G. Aad;B. Abbott;K. Abeling;N. J. Abicht;S. Abidi;A. Aboulhorma;H. Abramowicz;H. Abreu
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文献类型：
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作者：
G. Aad;B. Abbott;K. Abeling;N. J. Abicht;S. Abidi;A. Aboulhorma;H. Abramowicz;H. Abreu
本文介绍了在大型强子对撞机上对质子-质子碰撞中产生的四顶夸克（tt¯tt¯）的观测。利用ATLAS探测器收集的质量中心能量为13 TeV，利用140 fb - 1的积分光度进行分析。选择包含两个具有相同电荷的轻子或至少三个轻子（电子或介子）的事件。该方法利用事件运动学的多变量判别法将信号从背景中分离出来，并利用专用的控制区域对主导背景进行约束。相对于标准模型（SM）背景假设，测量到的tt¯tt¯信号的观察（预期）显著性为6.1（4.3）个标准差。测量到的tt¯tt¯生产截面为22.5-5.5+6.6 fb，与SM预测的12.0±2.4 fb在1.8个标准差内一致。数据还用于设置三个顶夸克产生横截面的限制，这是一个以前没有测量过的不可约背景，并约束影响tt¯tt¯产生的顶-希格斯汤川耦合和有效场论算子系数。
This paper presents the observation of four-top-quark (tt¯ tt¯) production in proton-proton collisions at the LHC. The analysis is performed using an integrated luminosity of 140 fb - 1 at a centre-of-mass energy of 13 TeV collected using the ATLAS detector. Events containing two leptons with the same electric charge or at least three leptons (electrons or muons) are selected. Event kinematics are used to separate signal from background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The observed (expected) significance of the measured tt¯ tt¯ signal with respect to the standard model (SM) background-only hypothesis is 6.1 (4.3) standard deviations. The tt¯ tt¯ production cross section is measured to be 22.5-5.5+6.6 fb, consistent with the SM prediction of 12.0 ± 2.4 fb within 1.8 standard deviations. Data are also used to set limits on the three-top-quark production cross section, being an irreducible background not measured previously, and to constrain the top-Higgs Yukawa coupling and effective field theory operator coefficients that affect tt¯ tt¯ production.