Probing the electromagnetic properties of the neutrinos at future lepton colliders

In this study, we explore the non-standard v (v) over bar gamma gamma couplings parametrized by dimension-seven operators via e(+)e(-) -> v (v) over bar gamma process at the FCC-ee/CEPC and mu(+)mu(-) -> v (v) over bar gamma process at the Muon Colliders. For the detailed Monte Carlo simulation, all signal and relevant background events are produced within the framework of Madgraph where non-standard v (v) over bar gamma gamma couplings are implemented. After passing through Pythia for parton showering and hadronization, detector effects are included via tuned corresponding detector cards for each collider in Delphes. Projected sensitivities on v (v) over bar gamma gamma couplings are obtained at a 5% confidence level without and with 5% systematic uncertainties for the FCC-ee/CEPC and the Muon Colliders, showcasing the complementarity between lepton colliders. Our best limit on the anomalous v (v) over bar gamma gamma couplings even with 5% systematic uncertainties for muon collider with root s = 10 TeV and L-int = 10 ab(-1) are found to be fourteen orders of magnitude stronger than the upper bound obtained from rare decay Z -> gamma gamma v (v) over bar analysis using LEP data.