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

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 sec- tion, using the recoil mass technique, sets the absolute scale for all Higgs coupling measurements. Previous studies have considered s (e+e --> HZ) with Z --> l+l-, where l = e, μ. 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 ps = 350 GeV at CLIC, s (e+e --> HZ) can be measured to ±1.8 % using the hadronic recoil mass technique. A similar precision is found for the ILC operating at ps = 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.