Model-independent ZH production cross section at FCC-ee

Abstract

This paper presents prospects for measuring the model-independent $ZH$ production cross section at the FCC-ee using the recoil-mass method at center-of-mass energies of 240 GeV and 365 GeV. Analyses are carried out in the muon, electron, and hadronic decay modes of the associated $Z$ boson. The event selections rely primarily on the kinematics of the reconstructed $Z$ decay products, ensuring maximal independence from specific Higgs boson decay modes, while multivariate techniques are employed to further enhance sensitivity. The statistical interpretation of the leptonic and hadronic final states at 240 GeV, with an integrated luminosity of 10.8 ab$^{-1}$, yields relative precisions of 0.52% for the combined leptonic channels and 0.38% for the hadronic channel. Their full statistical combination leads to total uncertainties of 0.31% at 240 GeV and 0.52% at 365 GeV, the latter assuming an integrated luminosity of 3.12 ab$^{-1}$. Dedicated statistical tests demonstrate model independence at the level of the obtained precision. This study presents the first consistent and combined analysis of the leptonic and hadronic final states for a model-independent $ZH$ cross-section measurement at a future lepton collider, using a unified workflow and covering both $\sqrt{s}=240$ and 365 GeV. It provides the most precise expected measurement of the $ZH$ production cross section at future lepton colliders, with the degree of model independence demonstrated within the achieved statistical precision.