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

Abstract : 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 a determination of the off-shell Higgs boson event yields normalised to the Standard Model prediction (signal strength) in the $ZZ \rightarrow 4\ell$, $ZZ\rightarrow 2\ell2\nu$ 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$^{\mathrm{-1}}$ 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 QCD 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 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.
Type de document :
Article dans une revue
European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2015, 75, pp.335. 〈10.1140/epjc/s10052-015-3542-2〉

http://hal.in2p3.fr/in2p3-01122472
Contributeur : Emmanuelle Vernay <>
Soumis le : mercredi 4 mars 2015 - 08:29:08
Dernière modification le : mardi 22 mai 2018 - 21:48:09

### Citation

G. Aad, S. Albrand, J. Brown, J. Collot, S. Crépé-Renaudin, et al.. Constraints of the off-shell Higgs boson signal strength in the high-mass $ZZ$ and $WW$ final states with the ATLAS detector. European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2015, 75, pp.335. 〈10.1140/epjc/s10052-015-3542-2〉. 〈in2p3-01122472〉

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