Abstract
A measurement of the Higgs boson production cross sections via associated WH and ZH production using H→WW⁎→ℓνℓν decays, where ℓ stands for either an electron or a muon, is presented. Results for combined WH and ZH production are also presented. The analysis uses events produced in proton–proton collisions collected with the ATLAS detector at the Large Hadron Collider in 2015 and 2016. The data correspond to an integrated luminosity of 36.1fb−1 recorded at a centre-of-mass energy of 13 TeV. The products of the H→WW⁎ branching fraction times the WH and ZH cross sections are measured to be 0.67−0.27+0.31(stat.)−0.14+0.18(syst.) pb and 0.54−0.24+0.31(stat.)−0.07+0.15(syst.) pb respectively, in agreement with the Standard Model predictions.
Highlights
Higgs boson production in association with a W or Z boson, which is respectively denoted by W H and Z H, and collectively referred to as V H associated production in the following, provides direct access to the Higgs boson couplings to weak bosons
The function has two independent scaling parameters: the signal strength parameter μ, defined as the ratio of the measured signal yield to that predicted by the Standard Model (SM), for each of the W H and the Z H processes
One Poisson probability term is added for each control regions (CRs) to determine simultaneously the normalisation of the corresponding background processes
Summary
Higgs boson production in association with a W or Z boson, which is respectively denoted by W H and Z H, and collectively referred to as V H associated production in the following, provides direct access to the Higgs boson couplings to weak bosons. Leptonic decays of τ leptons, from H → WW∗ → τντν or H → WW∗ → τν ν or from the associated vector bosons, are considered as signal, while no specific selection is performed for events with hadronically decaying τ leptons in the final state. In the W H channel, multivariate discriminants are used to maximise the sensitivity to the Higgs boson signal, while in the Z H channel the analysis is performed through selection requirements. The distribution of these W H discriminants, together with event counts in background control regions and the signal regions in the Z H channel, are combined in a binned maximum-likelihood fit to extract the signal yield and the background normalisations. The maximum-likelihood fit provides results for the W H and the Z H channels separately and for their combination V H, assuming the Standard Model (SM) prediction for the relative cross sections of the two production processes
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