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

G. Aad 1 S. Albrand 2 J. Brown 2 J. Collot 2 S. Crépé-Renaudin 2 P.A. Delsart 2 C. Gabaldon 2 M.H. Genest 2 J.Y. Hostachy 2 F. Ledroit-Guillon 2 A. Lleres 2 A. Lucotte 2 F. Malek 2 C. Monini 2 J. Stark 2 B. Trocmé 2 M. Wu 2 G. Rahal 3 S. Abdel Khalek 4 A. Bassalat 4 C. Becot 4 S. Binet 4 C. Bourdarios 4 D. Charfeddine 4 J.B. de Vivie De Regie 4 L. Duflot 4 M. Escalier 4 L. Fayard 4 D. Fournier 4 E.L. Gkougkousis 4 J.-F. Grivaz 4 T. Guillemin 4 F. Hariri 4 S. Henrot-Versillé 4 J. Hrivnac 4 L. Iconomidou-Fayard 4 M. Kado 4 A. Lounis 4 N. Makovec 4 C. Nellist 4 L. Poggioli 4 P. Puzo 4 A. Renaud 4 D. Rousseau 4 G. Rybkin 4 A.C. Schaffer 4 E. Scifo 4 L. Serin 4 S. Simion 4 R. Tanaka 4 H.L. Tran 4 D. Zerwas 4 Zhen Zhang 4 Z. Barnovska 5 N. Berger 5 M. Delmastro 5 L. Di Ciaccio 5 T.K.O. Doan 5 S. Elles 5 T. Hryn’ova 5 S. Jézéquel 5 I. Koletsou 5 R. Lafaye 5 J. Leveque 5 N. Massol 5 G. Sauvage 5 E. Sauvan 5 O. Simard 5 T. Todorov 5 I. Wingerter-Seez 5 D. Boumediene 6 Emmanuel Busato 6 D. Calvet 6 S. Calvet 6 J. Donini 6 E. Dubreuil 6 N. Ghodbane 6 G. Gilles 6 Ph. Gris 6 H. Liao 6 R. Madar 6 D. Pallin 6 S.M. Romano Saez 6 C. Santoni 6 D. Simon 6 Timothée Theveneaux-Pelzer 6 F. Vazeille 6 L. Alio 1 M. Barbero 1 Y. Coadou 1 C. Diaconu 1 S. Diglio 1 F. Djama 1 O. Duccu 1 L. Feligioni 1 J. Gao 1 G.D. Hallewell 1 F. Hubaut 1 S.J. Kahn 1 E. B. F. G. Knoops 1 E. Le Guirriec 1 J. Liu 7 K. Liu 1 D. Madaffari 1 K. Mochizuki 1 E. Monnier 1 S. Muanza 1 Y. Nagai 1 E. Nagy 1 P. Pralavorio 1 A. Rozanov 1 T. Serre 1 M. Talby 1 R.E. Ticse Torres 1 E. Tiouchichine 1 S. Tisserant 1 J. Toth 1 F. Touchard 1 L. Vacavant 1
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.
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European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2015, 75, pp.335. 〈10.1140/epjc/s10052-015-3542-2〉
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Soumis le : mercredi 4 mars 2015 - 08:29:08
Dernière modification le : mardi 22 mai 2018 - 21:48:09

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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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