Model-Independent Measurement of the e+e- -> HZ Cross Section at a Future e+e- Linear Collider using Hadronic Z Decays

TL;DR

This paper demonstrates a novel, model-independent method to measure the e+e- -> HZ cross section using hadronic Z decays at future linear colliders, achieving high precision and enhancing Higgs coupling studies.

Contribution

It extends the recoil mass technique to hadronic Z decays, significantly improving the statistical power of Higgs cross section measurements at future e+e- colliders.

Findings

Achieves 1.8% precision in measuring the HZ cross section at 350 GeV.

Extends recoil mass technique to Z->qq decays, increasing statistical sensitivity.

Supports initial operation of colliders just above top-pair threshold for optimal measurements.

Abstract

A future e+e- collider, such as the ILC or CLIC, would allow the Higgs sector to be probed with a precision significantly beyond that achievable at the High-Luminosity LHC. A central part of the Higgs programme at an e+e- collider is the model-independent determination of the absolute Higgs couplings to fermions and to gauge bosons. Here the measurement of the e+e-->HZ Higgsstrahlung cross section, using the recoil mass technique, sets the absolute scale for all Higgs coupling measurements. Previous studies have considered e+e- ->ZH with Z->l+l-, where l = electron or muon. In this paper it is shown for the first time that a near model-independent recoil mass technique can be extended to the hadronic decays of the Z boson. Because the branching ratio for Z->qq is approximately ten times greater than for Z->l+l-, this method is statistically more powerful than using the leptonic decays. For an integrated luminosity of 500 fb-1 at a centre-of-mass energy of 350 GeV at CLIC, the e+e-->HZ cross section can be measured to 1.8 % using the hadronic recoil mass technique. A similar precision is found for the ILC operating at 350 GeV. The centre-of-mass dependence of this measurement technique is discussed, arguing for the initial operation of a future linear collider at just above the top-pair production threshold.