High energy lepton colliders as the ultimate Higgs microscopes

TL;DR

This paper demonstrates that high-energy lepton colliders like ILC and CLIC can significantly improve bounds on electroweak/Higgs operators, probing scales up to tens of TeV and surpassing previous experimental limits.

Contribution

The study identifies key SMEFT operators relevant at high energies and performs a fit showing these colliders can explore unprecedented energy scales in Higgs physics.

Findings

Bounds surpass existing LEP and HL-LHC limits

Colliders can probe scales up to tens of TeV

High-energy fits improve sensitivity to SMEFT operators

Abstract

We study standard electroweak/Higgs processes at the high-energy lepton colliders ILC and CLIC. We identify a subset of three operators in the SMEFT that give leading contributions to these processes at high energies. We then perform a `high-energy fit' including these operators. Our final bounds surpass existing LEP bounds and HL-LHC projections by orders of magnitude. Furthermore, we find that these colliders can probe scales up to tens of TeV, corresponding to the highest scales explored in electroweak/Higgs physics.