Probing Neutral Triple Gauge Couplings via \(\boldsymbol{Z\gamma\,(\ell^+\ell^-\gamma)}\) Production at \(\boldsymbol{e^+e^-}\) Colliders

• Published in: arXiv.org 2024-07
• Main Authors: Liu, Danning, Rui-Qing, Xiao, Li, Shu, Ellis, John, Hong-Jian, He, Yuan, Rui
• Format: Article
• Language: English
• Subjects: Couplings; Electron-positron accelerators; Field theory; Form factors; Luminosity; Operators
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2404.15937

Neutral triple gauge couplings (nTGCs) are absent in the Standard Model (SM) and at the dimension-6 level in the Standard Model Effective Field Theory (SMEFT), arising first from dimension-8 operators. As such, they provide a unique window for probing new physics beyond the SM. These dimension-8 operators can be mapped to nTGC form factors whose structure is consistent with the spontaneously-broken electroweak gauge symmetry of the SM. In this work, we study the probes of nTGCs in the reaction \(e^+e^-\to Z\gamma\) with \(Z\to\ell^+\ell^-\,(\ell =e,\mu)\) at an \(e^+e^-\) collider. We perform a detector-level simulation and analysis of this reaction at the Circular Electron Positron Collider (CEPC) with collision energy \(\sqrt{s} = 240\) GeV and an integrated luminosity of 20 ab\(^{-1}\). We present the sensitivity limits on probing the new physics scales of dimension-8 nTGC operators via measurements of the corresponding nTGC form factors.