Sensitivities of prospective future e + e − colliders to decoupled new physics

Abstract

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, and FCC-ee EWPT measurements may be sensitive to $$ \Lambda = \mathcal{O}(30) $$ TeV. The prospective sensitivities of Higgs and TGC measurements at the ILC250 (FCC-ee) are to $$ \Lambda = \mathcal{O}(1) $$ TeV $$ \Lambda = \mathcal{O}(2) $$ TeV).