AI 中文总结
该研究利用CMS实验13 TeV质子-质子碰撞数据，通过机器学习算法识别喷注，对0.5-3 TeV质量范围的顶夸克亲和型Z'玻色子进行寻找，未发现超出标准模型的信号，给出了最严格的95%置信水平产生截面上限约束。
AI 中文摘要
本文介绍了对顶夸克亲和型Z'玻色子的寻找，其末态包含喷注及电子或μ子。该寻找基于欧洲核子中心（CERN）大型强子对撞机（LHC）的CMS实验在2016-2018年期间采集的质心系能量√s = 13 TeV的质子-质子碰撞数据样本，对应积分亮度为138 fb⁻¹。顶夸克亲和型Z'玻色子与顶夸克对（t¯t）伴随产生，且因仅与顶夸克耦合而衰变至t¯t对。本分析旨在鉴别产生洛伦兹 boosted 顶夸克的重Z'玻色子，这类顶夸克的强子衰变产物会合并为大半径喷注，研究中采用了机器学习算法来识别此类喷注。在Z'玻色子质量范围0.5-3 TeV内，以其质量的4%、10%、20%及50%作为固有宽度，将 transverse 动量最高的两个顶夸克候选粒子的不变质量分布作为判别变量。所得结果与标准模型背景预测相符，针对每个衰变宽度随Z'玻色子质量的函数，在95%置信水平下对其产生截面设置了上限。这些结果代表了迄今为止对顶夸克亲和型Z'玻色子存在性的最严格约束。
英文摘要
A search for a top-philic Z' boson in a final state with jets and an electron or muon is presented. The search is based on a sample of proton-proton collision data collected at $\sqrt{s}$ = 13 TeV by the CMS experiment at the CERN LHC during 2016$-$2018, corresponding to an integrated luminosity of 138 fb$^{-1}$. The top-philic Z' boson is produced in association with a top-antitop quark pair ($\mathrm{t\bar{t}}$) and decays into a $\mathrm{t\bar{t}}$ pair, as it couples exclusively to top quarks. The analysis aims to identify a heavy Z' boson that produces Lorentz-boosted top quarks, whose hadronic decay products are merged into large-radius jets. A machine-learning algorithm is employed to identify such jets. The distribution of the invariant mass of the two top quark candidates with the highest transverse momentum is used as the discriminant variable in a Z' boson mass range of 0.5$-$3 TeV, with intrinsic widths of 4, 10, 20, and 50% relative to its mass. The results obtained are found to be in agreement with the standard model background prediction. Upper limits at 95% confidence level are set on the production cross section of the Z' boson, for each of the decay widths as a function of its mass. These results represent the most stringent constraints to date on the existence of a top-philic Z' boson.
CommentsThis version has an updated author list. Submitted to the Journal of High Energy Physics. All figures and tables can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/B2G-24-009 (CMS Public Pages)
