Allbrooke, B M M, Asquith, L, Cerri, A, Chavez Barajas, C A, De Santo, A, Salvatore, F, Santoyo Castillo, I, Suruliz, K, Sutton, M R, Vivarelli, I and The ATLAS Collaboration, et al. (2015) Constraints on the off-shell Higgs boson signal strength in the high-mass ZZ and WW final states with the ATLAS detector. European Physical Journal C, 71 (335). ISSN 1434-6044
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Abstract
Measurements of the ZZ and WW final states in the mass range above the 2mZ and 2mW 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→4ℓ, ZZ→2ℓ2ν and WW→eνμν 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 √s=8 TeV. Using the CLs 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→ZZ and gg→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 ΓH/ΓHSM 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→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.
Item Type: | Article |
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Schools and Departments: | School of Mathematical and Physical Sciences > Physics and Astronomy |
Research Centres and Groups: | Experimental Particle Physics Research Group |
Subjects: | Q Science > QC Physics |
Depositing User: | Billy Wichaidit |
Date Deposited: | 27 Apr 2017 08:29 |
Last Modified: | 27 Apr 2017 08:44 |
URI: | http://srodev.sussex.ac.uk/id/eprint/67535 |
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📧 Request an updateProject Name | Sussex Project Number | Funder | Funder Ref |
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ATLAS | G0275 | STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL | ST/I006048/1 |