Observation and measurement of Higgs boson decays to WW* with the ATLAS detector

A. Aad, B. Abbott, J. Abdallah, S.A. Abdel Khalek, O. Abdinov, R. Aben, B. Abi, M. Abolins, O.S. AbouZeid, H. Abramowicz, Mogens Dam, Jørn Dines Hansen, Jørgen Beck Hansen, Stefania Xella, Peter Henrik Hansen, Troels Christian Petersen, Lotte Ansgaard Thomsen, Sascha Mehlhase, Morten Dam Jørgensen, Almut Maria PingelAsk Emil Løvschall-Jensen, Alejandro Alonso Diaz, James William Monk, Lars Egholm Pedersen, Graig Wiglesworth, Gorm Aske Gram Krohn Galster

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Abstract

We report the observation of Higgs boson decays to WWbased on an excess over background of 6.1 standard deviations in the dilepton final state, where the Standard Model expectation is 5.8 standard deviations. Evidence for the vector-boson fusion (VBF) production process is obtained with a significance of 3.2 standard deviations. The results are obtained from a data sample corresponding to an integrated luminosity of 25 fb-1from √s = 7 and 8 TeV pp collisions recorded by the ATLAS detector at the LHC. For a Higgs boson mass of 125.36 GeV, the ratio of the measured value to the expected value of the total production cross section times branching fraction is 1.09+0.16 -0.15(stat)+0.17 -0.14(syst). The corresponding ratios for the gluon fusion and vector-boson fusion production mechanisms are 1.02 ± 0.19(stat)+0.22 -0.18(syst) and 1.27+0.44 -0.40(stat)+0.30 -0.21(syst), respectively. At √s = 8 TeV, the total production cross sections are measured to be σ(gg→H→WW)=4.6±0.9(stat)+0.8 -0.7(syst) pb and σ(VBF H → WW)=0.51+0.17 -0.15(stat)+0.13 -0.08(syst)pb. The fiducial cross section is determined for the gluon-fusion process in exclusive final states with zero or one associated jet.

Original languageEnglish
Article number012006
JournalPhysical Review D (Particles, Fields, Gravitation and Cosmology)
Volume92
Issue number1
ISSN1550-7998
DOIs
Publication statusPublished - 16 Jul 2015

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