ATLAS collaboration (2824 authors)Aguilar-Saavedra, Juan AntonioAmor Dos Santos, Susana PatriciaAnjos, NunoAraque, Juan PedroCantrill, RobertCarvalho, JoãoCastro, Nuno FilipeConde Muiño, PatriciaDa Cunha Sargedas De Sousa, Mario JoseFiolhais, MiguelGalhardo, BrunoGomes, AgostinhoGonçalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AméliaManeira, JoséOnofre, AntónioPalma, AlbertoPedro, RutePina, João AntonioPinto, BelmiroSantos, HelenaSaraiva, JoãoSilva, JoséTavares Delgado, AdemarVeloso, FilipeWolters, Helmut2019-02-042019-02-042015-08-27http://dx.doi.org/10.1007/JHEP08(2015)137http://hdl.handle.net/10400.26/26866A search for Higgs boson production in association with a W or Z boson, in the H→ W W$^{∗}$ decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies $ \sqrt{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 two-lepton and three-lepton final states, while two- lepton and four-lepton final states are used to search for the ZH production mode. The observed significance, for the combined W H and ZH production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined W H and ZH signal yield to the Standard Model expectation, μ$_{V H}$ , is found to be μ$_{V H}$  = 3.0$_{− 1.1}^{+ 1.3}$ (stat.)$_{− 0.7}^{+ 1.0}$ (sys.) for the Higgs boson mass of 125.36 GeV. The W H and ZH production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the H → W W$^{∗}$ → ℓνℓν decay channel, resulting in an overall observed significance of 6.5 standard deviations and μ$_{ggF + VBF + VH}$ = 1. 16$_{− 0.15}^{+ 0.16}$ (stat.)$_{− 0.15}^{+ 0.18}$ (sys.). The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons (κ$_{V}$ ) and fermions (κ$_{F}$ ), the combined results are: |κ$_{V}$ | = 1.06$_{− 0.10}^{+ 0.10}$ , |κ$_{F}$ | = 0. 85$_{− 0.20}^{+ 0.26}$ .engjournal article2019-02-04