Determining Higgs boson width at electron-positron colliders

TL;DR

This paper proposes a model-independent method to measure the Higgs boson width at electron-positron colliders using multiple production and decay channels, achieving precise constraints without assuming fermion Yukawa interactions.

Contribution

It introduces a novel approach to determine Higgs width at $e^+e^-$ colliders within the SMEFT framework, independent of fermion Yukawa assumptions.

Findings

Higgs width can be measured at a few percent level.

Method applies to $ oot s=250$ and 350 GeV with 5 ab$^{-1}$.

Constraints on fermion Yukawa couplings are improved.

Abstract

Probing Higgs width $\Gamma_h$ is critical to test the Higgs properties. In this work we propose to measure $\Gamma_h$ at the $e^+e^-$ collider with a model-independent analysis under the Standard Model Effective Field Theory framework. We demonstrate that making use of the cross section measurements from $e^+e^-\to Zh$, $e^+e^-\to \nu_e\bar{\nu}_eh$ production and Higgs decay branching ratios $h\to WW^*/ZZ^*/\gamma\gamma$, one could determine $\Gamma_h$ at a percentage level with a center of mass energy $\sqrt{s}=250$ and 350 GeV and integrated luminosity $5~{\rm ab}^{-1}$. This conclusion would not depend on the assumption of the fermion Yukawa interactions. We further apply this result to constrain the fermion Yukawa couplings and it shows that the couplings could be well constrained.