论文标题
NLO QCD校正，以全面的脱壳生产$ t \ bar {t} z $，包括放血
NLO QCD corrections to full off-shell production of $t\bar{t}Z$ including leptonic decays
论文作者
论文摘要
在大型强子对撞机上，我们在TETRA-LEPTON衰减通道中的标准模型$ PP \ to t \ bar {t} z+x $过程中报告了NLO QCD校正对NLO QCD校正的计算。 This calculation is based on the matrix elements for the $e^+ ν_e\, μ^-\barν_μ\, b\bar{b} \,τ^+τ^-$ final state and includes all resonant and non-resonant Feynman diagrams, interferences and off-shell effects of the top quark as well as the $W$ and $Z$ gauge bosons.还包括光子诱导的贡献。由于习惯是此类研究，我们展示了固定和动力学分解和重态化量表的选择以及不同的PDF集的理论预测。此外，我们研究了与扰动扩张中被忽视的高阶项以及PDF集的参数化相关的主要理论不确定性。为了研究顶级衰减中的脱壳效果和高阶校正的大小，我们对此过程进行了第二次计算，该计算基于狭窄的宽度宽大含量，其中顶级夸克，$ w $和$ z $ g量规玻色子保存在壳上。为LHC Run II质量中心能源$ 13 $ TEV的综合和差异基准跨部门提供了结果。
Motivated by ongoing new physics searches in the top-quark sector at the Large Hadron Collider we report on the calculation of NLO QCD corrections to the Standard Model $pp\to t\bar{t}Z+X$ process in the tetra-lepton decay channel. This calculation is based on the matrix elements for the $e^+ ν_e\, μ^-\barν_μ\, b\bar{b} \,τ^+τ^-$ final state and includes all resonant and non-resonant Feynman diagrams, interferences and off-shell effects of the top quark as well as the $W$ and $Z$ gauge bosons. Also incorporated are photon-induced contributions. As it is customary for such studies, we show theoretical predictions for both fixed and dynamical factorisation and renormalisation scale choices and different PDF sets. Furthermore, we study the main theoretical uncertainties that are associated with neglected higher-order terms in the perturbative expansion and with the parameterisation of the PDF sets. In order to investigate the size of off-shell effects and higher-order corrections in top-quark decays, we perform a second computation for this process, which is based on the narrow-width-approximation where the top quarks, $W$ and $Z$ gauge bosons are kept on-shell. Results are given for the integrated and differential fiducial cross sections for the LHC Run II center-of-mass energy of $13$ TeV.
