Study of the Higgs boson decaying to $WW^{∗}$ produced in association with a weak boson with the ATLAS detector at the LHC

The search for Higgs boson production in association with a W or a Z boson, in the decay channel H→WW∗, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies s√=7 TeV and 8 TeV, corresponding to integrated luminosities of 4.5 fb−1 and 20.3 fb−1, respectively. The WH production mode is studied in three and two lepton final states, while a four lepton final state is used to search for ZH production. The observed significance is of 2.5 standard deviations while a significance of 0.9 standard deviations is expected for a Standard Model Higgs boson. The ratio of the combined WH and ZH signal yield to the Standard Model expectation, μVH, is found to be μVH=3.0+1.3−1.1(stat.)+1.0−0.7(sys.) for a Higgs boson mass of 125.36 GeV. The WH and ZH channels are also combined with the gluon-gluon fusion and vector boson fusion production modes studied in the H→WW∗→ℓνℓν decay channel. The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons (kV) and fermions (kF), the combined results are: |kV|=1.06+0.10−0.10, |kF|=0.85+0.26−0.20