Sensitivities of Prospective Future e+e- Colliders to Decoupled New Physics

We explore the indirect sensitivities to decoupled new physics of prospective precision electroweak measurements, triple-gauge-coupling measurements and Higgs physics at future $e^{+}{e}^{-}$ colliders, with emphasis on the ILC250 and FCC-ee. The Standard Model effective field theory (SM EFT) is adopted as a model-independent approach for relating experimental precision projections to the scale of new physics, and we present prospective constraints on the Wilson coefficients of dimension-6 operators. We find that in a marginalised fit ILC250 EWPT measurements may be sensitive to new physics scales $\Lambda = $\mathcal{O}$(10)$TeV,andFCC-eeEWPTmeasurementsmaybesensitiveto$\Lambda = $\mathcal{O}$(30)$~TeV. The prospective sensitivities of Higgs and TGC measurements at the ILC250 (FCC-ee) are to $\mathrm{\Lambda }=\mathcal{O}(1)$~TeV ($\mathrm{\Lambda }=\mathcal{O}(2)$~TeV).