Measuring the ratio of HW W and HZZ couplings through W +W −H production

Abstract

Abstract For a generic Higgs boson, measuring the relative sign and magnitude of its couplings with the W and Z bosons is essential in determining its origin. Such a test is also indispensable for the 125-GeV Higgs boson. We propose that the ratio of the HW W and HZZ couplings λ W Z can be directly determined through the W + W − H production, where H denotes a generic Higgs boson, owing to the tree-level interference effect. While this is impractical at the LHC due to the limited sensitivity, it can be done at future e + e − colliders, such as a 500-GeV ILC with the beam polarization P (e − , e +) = (−0.8, +0.3) in the jjℓ ± bb and ℓ ± ℓ ± ℓ ∓ jj channels. The discovery potential of a general ratio and the power to discriminate it from the SM value are studied in detail. Combining the cross section of e + e − → W + W − H with the measurements of HZZ coupling at the HL-LHC, one can further improve the sensitivity of λ W Z .