arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2312.04450hep-ex
收藏

利用ATLAS探测器在$\sqrt{s}=13$ TeV的$pp$碰撞中对$t\bar{t}Z$产生的单举和微分截面测量,包括EFT和自旋关联解释

Inclusive and differential cross-section measurements of $t\bar{t}Z$ production in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector, including EFT and spin-correlation interpretations

ATLAS Collaboration

AI总结:

本文利用ATLAS探测器在13 TeV质子-质子碰撞的140 fb$^{-1}$数据测量了$t\bar{t}Z$产生的单举和微分截面,结果与标准模型一致,并在EFT框架下限制维度-6算符,首次测量了$t\bar{t}Z$自旋关联。

摘要:

本文给出了顶夸克-反顶夸克对与$Z$玻色子伴随产生($t\bar{t}Z$)的单举和微分产生截面的测量结果。测量针对具有两个、三个或四个孤立轻子(电子或μ子)的末态。测量使用了ATLAS探测器在大型强子对撞机上于2015-2018年间记录的$\sqrt{s}=13$ TeV的$pp$碰撞数据,对应的积分亮度为$140$ fb$^{-1}$。测得单举截面为$σ_{t\bar{t}Z}= 0.86 \pm 0.04~\mathrm{(stat.)} \pm 0.04~\mathrm{(syst.)}~$pb,发现与最先进的标准模型预言一致。微分测量以多个探测$t\bar{t}Z$系统运动学的观测量为函数给出。绝对和归一化微分截面测量均在粒子级和部分子级针对特定基准体积进行,并与NLO+NNLL理论预言进行了比较。结果在标准模型有效场论框架下进行解释,并用于对大量涉及顶夸克的维度-6算符设置限制。本文首次给出了$t\bar{t}Z$事例中自旋关联的测量:结果与标准模型预期一致,无自旋关联的零假设以$1.8$个标准偏差的显著性被否定。

英文摘要:

Measurements of both the inclusive and differential production cross sections of a top-quark-top-antiquark pair in association with a $Z$ boson ($t\bar{t}Z$) are presented. Final states with two, three or four isolated leptons (electrons or muons) are targeted. The measurements use the data recorded by the ATLAS detector in $pp$ collisions at $\sqrt{s}=13$ TeV at the Large Hadron Collider during the years 2015-2018, corresponding to an integrated luminosity of $140$ fb$^{-1}$. The inclusive cross section is measured to be $σ_{t\bar{t}Z}= 0.86 \pm 0.04~\mathrm{(stat.)} \pm 0.04~\mathrm{(syst.)}~$pb and found to be in agreement with the most advanced Standard Model predictions. The differential measurements are presented as a function of a number of observables that probe the kinematics of the $t\bar{t}Z$ system. Both the absolute and normalised differential cross-section measurements are performed at particle level and parton level for specific fiducial volumes, and are compared with NLO+NNLL theoretical predictions. The results are interpreted in the framework of Standard Model effective field theory and used to set limits on a large number of dimension-6 operators involving the top quark. The first measurement of spin correlations in $t\bar{t}Z$ events is presented: the results are in agreement with the Standard Model expectations, and the null hypothesis of no spin correlations is disfavoured with a significance of $1.8$ standard deviations.

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。

↑