Study of (W/Z)H production and Higgs boson couplings using H→ W W ^*decays with the ATLAS detector

A 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 √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 .. Authors: Aad, G.; Abbott, B.; Abdallah, J.; Abdinov, O.; Aben, R.. Subjects: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS