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

The measurements 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 \(\Gamma _H/\Gamma _H^{\mathrmmore » {SM}}\) 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.« less
  1. Aix-Marseille Univ. and CNRS/IN2P3, Marseille (France). et al.
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC03-76SF00515; AC02-06CH11357; AC02-98CH10886; AC02-05CH11231; SC00112704
Accepted Manuscript
Journal Name:
European Physical Journal. C, Particles and Fields
Additional Journal Information:
Journal Volume: 75; Journal Issue: 7; Journal ID: ISSN 1434-6044
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Contributing Orgs:
ATLAS Collaboration
Country of Publication:
United States