"Table 50" of "Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at $\sqrt{s}=13$ TeV"

Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than $355$ GeV and the other top quark decays into $\ell \nu b$ are presented using 139 fb$^{-1}$ of data collected by the ATLAS experiment during proton--proton collisions at the LHC. The fiducial cross-section at $\sqrt{s}=13$ TeV is measured to be $\sigma = 1.267 \pm 0.005 \pm 0.053$ pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of $4.2\%$. The cross-section is measured differentially as a function of variables characterising the $t\bar{t}$ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to search for new physics in the context of the effective field theory framework. No significant deviation from the Standard Model is observed and limits are set on the Wilson coefficients of the dimension-six operators $O_{tG}$ and $O_{tq}^{(8)}$, where the limits on the latter are the most stringent to date.

本文利用大型强子对撞机（LHC）上ATLAS实验采集的139 fb⁻¹质子-质子对撞数据，报告了强衰变顶夸克横向动量（transverse momentum）大于355 GeV、另一顶夸克衰变至ℓνb末态的顶夸克对产生截面测量结果。在质心系能量√s=13 TeV条件下，测得基准截面（fiducial cross-section）为σ=1.267±0.005±0.053 pb，其中不确定度分别来自数据事件统计量有限带来的统计不确定度与系统不确定度（systematic uncertainties），总不确定度为4.2%。针对刻画t$ar{t}$系统与事件中额外辐射的各类变量，本文开展了微分截面测量。将上述测量结果与多款蒙特卡洛发生器（Monte Carlo generators）的理论预言进行对比，其中包含将发生器重新加权以匹配次次领头阶（next-to-next-to-leading order）部分子层次计算的对比方案。该重新加权处理提升了实验数据与理论预言之间的吻合程度。利用测得的顶夸克横向动量分布，在有效场论（effective field theory）框架下开展新物理搜寻。未观测到与标准模型（Standard Model）存在显著偏离，并对六维算符$O_{tG}$与$O_{tq}^{(8)}$的威尔逊系数（Wilson coefficients）设置了约束，其中针对后者的约束为迄今最严苛的结果。