Tracing Neutrino Non-Standard Interactions through Charged Lepton Collisions

Neutrino non-standard interactions (NSI) play a crucial role in neutrino oscillations and can provide valuable insights for constructing models of neutrino masses and mixing. While NSI have been widely explored through oscillation and scattering experiments, as well as in cosmological and astrophysical contexts, we focus on probing them at future lepton colliders like the ILC, CLIC, and FCC-$ee$. If NSI arise from heavy mediators above the electroweak scale, these colliders can offer superior sensitivity compared to neutrino experiments across a broad mass range. A notable outcome is that lepton collider data can help resolve parameter degeneracies seen in oscillation studies. We find that large NSI scenarios, proposed to address the tension between T2K and NO$ν$A results, can be completely tested at such collider facilities. We also explore the potential of future colliders like the FCC to probe leptonic NSI using lepton PDFs in proton-proton collisions.