发表机构
Mohammed V University in Rabat（拉巴特穆罕默德五世大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用顶夸克自旋关联，在HL-LHC双轻子道中区分赝标量与矢量$t\bar t$共振态，通过螺旋度关联差异和重建方法，在3000 fb⁻¹下实现约2-3标准差的区分，并指出限制因素。
AI 中文摘要
顶夸克自旋关联为探测衰变至$t\bar t$的共振态的量子数提供了直接探针。我们在双轻子道中比较了CP奇性II型双希格斯二重态模型赝标量$A$与自旋为1的轻子phobic topcolor $Z'$。两种假设在部分子层次螺旋度关联上的差异为$\Delta c_{\rm hel}\simeq0.43$，几乎与质量无关，而中微子加权重建通过约0.66的有效稀释因子保持了这一区分度。在400和800 GeV处，赝标量的归一化锚定于CMS HIG-22-013耦合限制，而$Z'$的产率与赝标量匹配，使得比较主要检验自旋结构。仅含领头阶$t\bar t$的投影在$3000\\,{\rm fb}^{-1}$亮度下预期区分度为2.27和2.74个标准差。将选定信号产率相等化后，纯自旋形状区分度为1.86和2.70个标准差。对高斯约束的标准模型$c_{\rm hel}$形状 nuisance 进行剖面化，在乐观边带基准下给出2.07和2.63个标准差，或在较弱约束下给出1.67和2.26个标准差。局部固定模板外推对应于在耦合强度高于参考值约22%和16%时达到五个标准差的区分能力。单独展示了1500 GeV $g=1$的点。其探测能力受限于亚百分比的信号占比以及对质量依赖的标准模型自旋形状的控制，而非内在的共振自旋区分度。
英文摘要
Top-quark spin correlations provide a direct probe of the quantum numbers of a resonance decaying to $t\bar t$. We compare a CP-odd type-II two-Higgs-doublet-model pseudoscalar $A$ with a spin-1 leptophobic topcolor $Z'$ in the dilepton channel. The two hypotheses differ in the parton-level helicity correlation by $Δc_{\rm hel}\simeq0.43$, nearly independently of mass, and neutrino-weighted reconstruction preserves this separation with an effective dilution factor of about 0.66. At 400 and 800 GeV, the pseudoscalar normalization is anchored to CMS HIG-22-013 coupling limits, while the $Z'$ rate is matched to the pseudoscalar so that the comparison primarily tests spin structure. The leading-order $t\bar t$-only projection gives expected separations of 2.27 and 2.74 standard deviations at $3000\,{\rm fb}^{-1}$. Equalizing the selected signal yields gives pure spin-shape separations of 1.86 and 2.70 standard deviations. Profiling a Gaussian-constrained Standard Model $c_{\rm hel}$-shape nuisance gives 2.07 and 2.63 standard deviations for an optimistic sideband benchmark, or 1.67 and 2.26 for a weaker constraint. A local fixed-template extrapolation corresponds to five-standard-deviation discrimination at couplings about 22\% and 16\% above the reference values. A 1500 GeV $g=1$ point is shown separately. The reach is limited by the sub-percent signal fraction and control of the mass-dependent Standard Model spin shape, rather than by the intrinsic resonance-spin separation.
Comments12 pages, 9 figures. Submitted to Physical Review D
