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Constraints on the off-shell Higgs boson signal strength in the high-mass $ZZ$ and $WW$ final states with the ATLAS detector

2015-07-17Journal article Open access
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dc.contributor.authorATLAS collaboration (2820 authors)
dc.contributor.authorAguilar-Saavedra, Juan Antonio
dc.contributor.authorAmor Dos Santos, Susana Patricia
dc.contributor.authorAnjos, Nuno
dc.contributor.authorAraque, Juan Pedro
dc.contributor.authorCantrill, Robert
dc.contributor.authorCarvalho, João
dc.contributor.authorCastro, Nuno Filipe
dc.contributor.authorConde Muiño, Patricia
dc.contributor.authorDa Cunha Sargedas De Sousa, Mario Jose
dc.contributor.authorFiolhais, Miguel
dc.contributor.authorGalhardo, Bruno
dc.contributor.authorGomes, Agostinho
dc.contributor.authorGonçalo, Ricardo
dc.contributor.authorJorge, Pedro
dc.contributor.authorLopes, Lourenco
dc.contributor.authorMachado Miguens, Joana
dc.contributor.authorMaio, Amélia
dc.contributor.authorManeira, José
dc.contributor.authorOnofre, António
dc.contributor.authorPalma, Alberto
dc.contributor.authorPedro, Rute
dc.contributor.authorPina, João Antonio
dc.contributor.authorPinto, Belmiro
dc.contributor.authorSantos, Helena
dc.contributor.authorSaraiva, João
dc.contributor.authorSilva, José
dc.contributor.authorTavares Delgado, Ademar
dc.contributor.authorVeloso, Filipe
dc.contributor.authorWolters, Helmut
dc.date.accessioned2019-02-04T06:13:14Z
dc.date.available2019-02-04T06:13:14Z
dc.date.issued2015-07-17
dc.date.updated2019-02-04T06:13:14Z
dc.description.abstractMeasurements of the ZZ and WW final states in the mass range above the $2m_Z$ and $2m_W$ thresholds provide a unique opportunity to measure the off-shell coupling strength of the Higgs boson. This paper presents constraints on the off-shell Higgs boson event yields normalised to the Standard Model prediction (signal strength) in the $ZZ \rightarrow 4\ell $ , $ZZ\rightarrow 2\ell 2\nu $ and $WW\rightarrow e\nu \mu \nu $ final states. The result is based on pp collision data collected by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 20.3 fb$^{-1}$ at a collision energy of $\sqrt{s}=8$  TeV. Using the $CL_s$ method, the observed 95  $\%$ confidence level (CL) upper limit on the off-shell signal strength is in the range 5.1–8.6, with an expected range of 6.7–11.0. In each case the range is determined by varying the unknown $gg\rightarrow ZZ$ and $gg\rightarrow WW$ background K-factor from higher-order quantum chromodynamics corrections between half and twice the value of the known signal K-factor. Assuming the relevant Higgs boson couplings are independent of the energy scale of the Higgs boson production, a combination with the on-shell measurements yields an observed (expected) 95  $\%$ CL upper limit on $\Gamma _H/\Gamma _H^{\mathrm {SM}}$ in the range 4.5–7.5 (6.5–11.2) using the same variations of the background K-factor. Assuming that the unknown $gg\rightarrow VV$ background K-factor is equal to the signal K-factor, this translates into an observed (expected) 95  $\%$ CL upper limit on the Higgs boson total width of 22.7 (33.0) MeV.
dc.description.versionPeer Reviewed
dc.identifierEur.Phys.J. C75 (2015) 335; DOI 10.1140/epjc/s10052-015-3542-2
dc.identifier.urihttp://dx.doi.org/10.1140/epjc/s10052-015-3542-2
dc.identifier.urihttp://hdl.handle.net/10400.26/26794
dc.language.isoeng
dc.titleConstraints on the off-shell Higgs boson signal strength in the high-mass $ZZ$ and $WW$ final states with the ATLAS detector
dc.typejournal article
dspace.entity.typePublication
rcaap.rightsopenAccesspt
rcaap.typearticle

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