Paper detail

Probing Neutral Triple Gauge Couplings with $Z^* γ\, (ν\bar νγ)$ Production at Hadron Colliders

We study probes of neutral triple gauge couplings (nTGCs) via $Z^*γ$ production followed by off-shell decays $Z^*\toν\barν$ at the LHC and future $pp$ colliders, including both CP-conserving (CPC) and CP-violating (CPV) couplings. We present the dimension-8 SMEFT operators contributing to nTGCs and derive the correct form factor formulation for the off-shell vertices $Z^*γV^*$ ($V=Z,γ$) by matching them with the dimension-8 SMEFT operators. Our analysis includes new contributions enhanced by the large off-shell momentum of $Z^*$, beyond those of the conventional $ZγV^*$ vertices with on-shell $Zγ$. We analyze the sensitivity reaches for probing the CPC/CPV nTGC form factors and the new physics scales of the dimension-8 nTGC operators at the LHC and future 100TeV $pp$ colliders. We compare our new predictions with the existing LHC measurements of CPC nTGCs in the $ν\barνγ$ channel and demonstrate the importance of our new method.