Radion--QCD干涉在HL-LHC的$t\bar t$产生中的研究：有限顶夸克质量效应与预期灵敏度

中文摘要 AI 辅助

我们研究了高亮度大型强子对撞机中顶夸克对产生过程中重radion与QCD连续态的干涉，将数值研究限制在纯radion极限$\xi=0$。胶子融合振幅结合了QCD迹反常与精确的有限顶夸克质量圈型因子，其相干和决定了产生系数的大小和相位。在顶阈值之上，圈图发展出吸收部分，使产生系数变为复数，从而允许干涉在共振极点处保持非零，而纯实数点状系数在该处将给出零干涉。该复数系数通过原生圈诱导实现和公共事件相位基构造独立验证。由此产生的信号特征是峰-谷形变而非正凸起，而探测器涂抹将窄的真实级结构转变为宽的子百分比畸变。对于$\sqrt{s}=14$ TeV下的$3\\,\mathrm{ab}^{-1}$数据，我们构建了基于ATLAS锚定的唯象响应，并进行了精确的分箱泊松Asimov分析，其中背景归一化自由且存在相关的形状干扰项。对于$0.1\\%$形状基准和$50$ GeV相关长度，在radion质量为$600$、$800$、$1000$、$1200$和$1500$ GeV时，轮廓化中位数$95\\%$ $CL_s$对$\Lambda_r$的排除限分别为$2.49$、$2.82$、$3.00$、$2.56$和$2.19$ TeV。在$800$ GeV处的诊断分解给出共振平方项单独的$2.18$ TeV和干涉项单独的$2.83$ TeV。一个选定背景形变压力测试在很大程度上消除了约$1$ TeV处的表观最大值，表明其位置和显著性依赖于归一化方案，但核心结论不变：预期灵敏度主要由干涉驱动。

英文摘要

We investigate the interference of a heavy radion with the QCD continuum in top-quark-pair production at the High-Luminosity Large Hadron Collider, restricting the numerical study to the pure-radion limit $ξ=0$. The gluon-fusion amplitude combines the QCD trace anomaly with the exact finite-top-mass loop form factor, whose coherent sum fixes both the magnitude and the phase of the production coefficient. Above the top threshold the loop develops an absorptive part, rendering the production coefficient complex and allowing the interference to remain non-zero on the resonance pole, where a purely real point-like coefficient would give none. The complex coefficient is validated independently using a native loop-induced implementation and a common-event phase-basis construction. The resulting signature is a peak--dip deformation rather than a positive bump, while detector smearing turns the narrow truth-level structure into a broad sub-percent distortion. For $3\,\mathrm{ab}^{-1}$ at $\sqrt{s}=14$ TeV, we construct an ATLAS-anchored phenomenological response and perform an exact binned Poisson Asimov analysis with a free background normalization and a correlated shape nuisance. For a $0.1\%$ shape benchmark with a $50$ GeV correlation length, the profiled median $95\%$ $CL_s$ reach in $Λ_r$ is $2.49$, $2.82$, $3.00$, $2.56$, and $2.19$ TeV for radion masses of $600$, $800$, $1000$, $1200$, and $1500$ GeV, respectively. A diagnostic decomposition at $800$ GeV gives $2.18$ TeV for the resonance-squared term alone and $2.83$ TeV for the interference term alone. A selected-background deformation stress test largely removes the apparent maximum near $1$ TeV, showing that its location and prominence are normalization-prescription dependent, while leaving the central conclusion unchanged: the projected sensitivity is predominantly interference driven.

发表机构

• Laboratory of Condensed Matter and Interdisciplinary Sciences, Unité de Recherche Labellisée CNRST (URL-CNRST), Faculty of Sciences, Mohammed V University in Rabat（拉巴特穆罕默德五世大学理学院凝聚态物质与跨学科学实验室，CNRST认证研究单位）

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17 pages, 15 figures