标题： 标量轻子夸克模型中通过顶夸克极化进行喷注结构探测 显示英文标题

标题： Jet Substructure Probe on Scalar Leptoquark Models via Top Polarization

摘要： 研究轻子夸克及其与不同手性费米子的耦合，为区分不同的轻子夸克模型提供了一个强有力的工具。 作为案例研究，我们关注两种特定的第三代标量轻子夸克模型，$S_3$和$R_2$，它们在弱电量子数和与顶夸克的耦合手性结构上有所不同，从而导致不同的顶夸克极化状态。 为了提高分析的有效性，我们采用了如 Soft Drop、$N$-subjettiness 以及我们自定义的$b$-tagging 方法等喷注子结构技术，以及其他事件变量。 分析使用了固定半径和动态半径喷注聚类算法进行。 使用提升决策树（BDT）的多变量分析来隔离标准模型背景中的信号。 对于轻子夸克质量为 1250 GeV 的情况，分析在 14 TeV 的 HL-LHC 上实现了高达$5.3\,\sigma$的信号显著性。 此外，应用基于$CL_s$的轮廓似然估计器来区分极化敏感变量，以区分这两种模型。 为了增强两个模型之间的分离，通过训练一个BDT网络来区分$S_3$和$R_2$模型，获得了一个额外的BDT分类器得分。 在选定的信号区域中，BDT分类器得分提供的分离度高达$3.2\,\sigma$，优于传统的变量如$E_b/E_t$和$\cos\theta_b$。 显示英文摘要

摘要： The study of leptoquarks and their couplings to fermions with different chiralities provides a powerful tool for distinguishing among different leptoquark models. As a case study, we focus on two specific third-generation scalar leptoquark models, $S_3$ and $R_2$, which differ in their electroweak quantum numbers and chiral structures of couplings to the top quark, leading to distinct top-quark polarization states. To enhance the efficacy of the analysis, we employ jet substructure techniques like Soft Drop, $N$-subjettiness, and our custom $b$-tagging method, along with other event variables. The analysis has been performed using both fixed radius and dynamic radius jet clustering algorithms. A multivariate analysis using a boosted decision tree (BDT) is performed to isolate signal from the Standard Model background. For a leptoquark mass of 1250 GeV, the analysis achieves a signal significance of up to $5.3\,\sigma$ at the 14 TeV HL-LHC. Furthermore, a $CL_s$-based profile likelihood estimator is applied to polarization-sensitive variables to discriminate between the two models. To enhance separation between the two models, an additional BDT classifier score is obtained by training a BDT network to distinguish between the $S_3$ and $R_2$ models. In the chosen signal region, the BDT classifier score provides a separation score of up to $3.2\,\sigma$, outperforming traditional variables such as $E_b/E_t$ and $\cos\theta_b$.