Higgs, top and electro-weak precision measurements at future $e^+ e^-$ colliders; a combined effective field theory analysis with renormalization mixing

TL;DR

This study evaluates how future electron-positron colliders can constrain the Standard Model Effective Field Theory, focusing on Higgs, top, and electroweak sectors, using a combined global fit approach with renormalization group mixing.

Contribution

It introduces a comprehensive global fit analysis with an extended parameter basis, incorporating renormalization group effects, to assess future collider sensitivities to SMEFT operators.

Findings

Higgs couplings are robust against top operator effects.

Top operators significantly impact bounds on Wilson coefficients.

Including 500 GeV ILC data yields robust bounds on all parameters.

Abstract

This paper presents a combined analysis of the potential of a future electron-positron collider to constrain the Higgs, top and electro-weak (EW) sectors of the Standard Model Effective Field Theory (SMEFT). The leading contributions of operators involving top quarks arise mostly at one-loop suppressed order and can be captured by the renormalization group mixing with Higgs operators. We perform global fits with an extended basis of 29 parameters, including both Higgs and top operators, to the projections for the Higgs, top and electro-weak precision measurements at the International Linear Collider (ILC). The determination of the Higgs boson couplings in the 250 GeV stage of the ILC is initially severely degraded by the additional top-quark degrees of freedom, but can be nearly completely recovered by the inclusion of precise measurements of top-quark EW couplings at the LHC. The physical Higgs couplings are relatively robust, as the top mass is larger than the energy scale of EW processes. The effect of the top operators on the bounds on the Wilson coefficients is much more pronounced and may limit our ability to identify the source of deviations from the Standard Model. Robust global bounds on all Wilson coefficients are only obtained when the 500 GeV stage of the ILC is included.