当前LHC数据中的电弱单顶夸克与单顶夸克协同阴谋
Electroweak and Single Top-Quark Conspiracy in Current LHC Data
中文总结 AI 辅助
该研究结合LHC数据与SMEFT分析识别出特定算符模式，探究规范不变模型重现该模式的可行性，提出含多阈值类矢量夸克区的最小方案，并指出相关测量与搜寻方向。
中文摘要 AI 辅助
近期LHC对电弱单顶夸克产生及顶夸克协同希格斯玻色子产生的测量显示出若干事例率偏移，而相关的多玻色子道仍接近其标准模型预言。规范对称性将这些过程关联起来，使得偏差可被整理为共同紫外起源的低能印记。结合Z极点可观测量对这些事例率进行的标准模型有效场论（SMEFT）分析，识别出如下模式：弱顶偶极子和三规范形变项的 pull 值最大，伴随正的左手顶夸克流；当纯三规范系数设为零时，也能获得可接受的拟合。我们随后探究是否存在规范不变模型可产生这组算符，且仍能通过实验数据的诸多约束。在弱耦合可重整匹配框架内，单个标量、矢量或类矢量夸克多重态不足以重现完整模式。最小的可行方案是多阈值类矢量夸克区（一个单态、一个二重态及两个三重态），其流在树图水平产生，而偶极子则需要当前区未确定的额外圈图动力学。一个代表性实现方案在面对直接、间接及味约束时，指向电弱单顶夸克产生的关联测量、提升的tH和t\bar{t}H灵敏度，以及更新的类矢量夸克搜寻。
英文摘要
Recent LHC measurements of electroweak single top-quark and top-quark associated Higgs boson production show a number of rate shifts, while related multiboson channels remain close to their Standard Model predictions. Gauge symmetry relates these processes such that deviations can be organised as the low-energy imprint of a common ultraviolet origin. A Standard Model Effective Field Theory (SMEFT) analysis of these rates together with $Z$-pole observables identifies the pattern: a weak top dipole and a triple-gauge deformation carry the largest pulls, accompanied by a positive left-handed top-quark current. An acceptable fit is also obtained with the pure triple-gauge coefficient set to zero. We then ask whether a gauge-invariant model can produce this set of operators and still pass the numerous constraints from experimental data. Within weakly coupled renormalisable matching, no single scalar, vector or vector-like-quark multiplet is sufficient to reproduce the full pattern. A minimal possibility is a multi-threshold vector-like-quark sector (a singlet, a doublet and two triplets) whose currents arise at tree level, while the dipole requires additional loop dynamics that the current sector does not fix. A representative realisation, confronted with direct, indirect and flavour constraints, points to correlated measurements of electroweak single top-quark production, improved $tH$ and $t \bar t H$ sensitivity, and updated searches for vector-like quarks.
