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

TL;DR

This paper assesses how future electron-positron colliders like ILC250 and FCC-ee can indirectly detect decoupled new physics through precision measurements, using effective field theory to estimate sensitivity to high energy scales.

Contribution

It provides model-independent projections of the sensitivity of future colliders to new physics scales via electroweak, Higgs, and gauge coupling measurements using the Standard Model effective field theory.

Findings

ILC250 EWPT may probe new physics scales around 10 TeV.

FCC-ee EWPT may reach sensitivities near 30 TeV.

Higgs and TGC measurements could detect new physics at 1-2 TeV.

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).