利用ATLAS探测器在质心系能量√s=13TeV的质子-质子碰撞中观测s道单顶夸克产生
Observation of single top-quark production in the $s$-channel in proton--proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
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中文总结 AI 辅助
利用ATLAS探测器在√s=13TeV的质子-质子碰撞中，通过图神经网络区分本底，观测到s道单顶夸克产生，信号显著性达5.1倍标准偏差，测得的产生截面与标准模型预测一致。
中文摘要 AI 辅助
本文报告了首个单实验对s道单顶夸克产生的观测结果。对该过程的测量对于完整表征顶夸克的电弱相互作用以及探测新物理至关重要，然而其被高度压低的产生截面迄今使其在大型强子对撞机中未能被直接探测到。本分析使用ATLAS探测器采集的质心系能量√s=13TeV的质子-质子碰撞数据，对应积分亮度为140 fb⁻¹。所选事例包含恰好一个电子或μ子、缺失横动量以及恰好两个由b夸克引发的喷注。研究采用图神经网络（Graph Neural Network）将信号与顶夸克对、W+喷注以及t道单顶夸克本底区分开来。对该网络输出进行似然拟合得到观测（预期）的信号显著性为5.1（5.2）个标准偏差。测得的产生截面σ_{t\bar{b}+\bar{t}b}=10.8±1.5（统计）±1.6（系统）pb，与标准模型预测一致。
英文摘要
The first single-experiment observation of single top-quark production in the $s$-channel is presented. Measurements of this process are essential to fully characterize the electroweak interactions of the top quark and probe for new physics, however its highly suppressed cross-section has so far caused it to evade direct detection at the Large Hadron Collider. The analysis uses proton--proton collision data collected at a center-of-mass energy of $\sqrt{s}=13$ TeV with the ATLAS detector, corresponding to an integrated luminosity of $140$ fb$^{-1}$. The selected events contain exactly one electron or muon, missing transverse momentum, and exactly two $b$-quark-initiated jets. A Graph Neural Network is utilized to separate the signal from the top-quark pair, $W$+jets, and $t$-channel single top-quark backgrounds. A likelihood fit to the network output yields an observed (expected) signal significance of $5.1$ ($5.2$) standard deviations. The measured cross-section of $σ_{t\bar{b}+\bar{t}b} = 10.8 \pm 1.5 \text{ (stat.)} \pm 1.6 \text{ (syst.)}\,\text{pb}$ is consistent with the Standard Model prediction.
发表机构
- EUROPEAN ORGANISATION FOR NUCLEAR RESEARCH (CERN)（欧洲核子研究中心）
机构由 AI 辅助整理，请以论文原文为准。
