Searches for anomalous neutral triple gauge boson couplings (NTGCs) provide important tests for the gauge structure of the standard model. In SMEFT ("standard model effective field theory") NTGCs appear only at the level of dimension-8 operators. While the phenomenology of these operators has been discussed extensively in the literature, renormalizable UV models that can generate these operators are scarce. In this work, we study a variety of extensions of the SM with heavy fermions and calculate their matching to d = 8 NTGC operators. We point out that the complete matching of UV models requires four different CP-conserving d = 8 operators and that the single CPC d = 8 operator, most commonly used by the experimental collaborations, does not describe all possible NTGC form factors. Despite stringent experimental constraints on NTGCs, limits on the scale of UV models are relatively weak, because their contributions are doubly suppressed (being d = 8 and 1-loop). We suggest a series of benchmark UV scenarios suitable for interpreting searches for NTGCs in the upcoming LHC runs, obtain their current limits and provide estimates for the expected sensitivity of the high-luminosity LHC.
On the Experimental Effects of the Off-shell Structure in Anomalous Neutral Triple Gauge Vertices
我们讨论了在寻找异常中性三重规范耦合$\mathrm{e^+ e^-}$碰撞壳和壳外处理之间的差异。我们发现，通常的外壳框架代表了一个最佳的起点，涵盖了所有的情况下，预计一个合理的实验灵敏度。我们表明，离壳效应导致在实验水平上的偏差可以忽略不计，只要$\mathrm{e^+ e^-}\to\mathrm{f}\bar{\mathrm{f}}γ$和$\mathrm{e^+ e^-}\to\mathr performed in regions where $ \mathrm{Z}^* \to \mathrm{f} \bar{\mathrm{f}}，\mathrm{f^\prime} \math生产是占主导地位的。出于一致性的原因，我们提倡使用对外壳上定义的自然扩展，它考虑了正确的外壳外依赖。与文献中最近提出的相反，我们发现在一般情况下，中性三规范耦合之间没有$SU(2)_L\times U(1)_Y$约束。
