Journal Article

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

Petteni, M., Walkowiak, W., Fiascaris, M., Cuhadar Donszelmann, T., Grancagnolo, F., Lucotte, A., Zanzi, D., Strom, D. M., Meyer, J-P., Wittig, T., Grohsjean, A., Hines, E., Hasegawa, S., Friedrich, C., Fabbri, L., Giunta, M., Aguilar-Saavedra, J. A., Carminati, L., Cantero, J., Hubaut, F., Hsu, S.-C., Pedro, R., Gregersen, K., Meyer, C., Hengler, C., Abolins, M., Mellado Garcia, B. R., Diaz, M. A., Dudarev, A., Oren, Y., Borissov, G., Kajomovitz, E., Garberson, F., Yang, Y., Beddall, A., De Lorenzi, F., Catmore, J. R., Calafiura, P., Gonzalez-Sevilla, S., Korn, A., Skinnari, L. A., Laplace, S., AbouZeid, O. S., Moser, H. G., Blanchard, J.-B., Kim, H., Schwindling, J., Hessey, N. P., Schaefer, D., Carter, J. R., Golubkov, D., Krüger, H., Blum, W., Butti, P., Oussoren, K. P., Gazis, E. N., Batley, J. R., Vokac, P., Hawkings, R. J., Lee, J. S. H., Ahlen, S. P., Becker, S., Hall, D., Stapnes, S., Levin, D., Yildirim, E., Barlow, N., Zoccoli, A., Schuh, N., Jia, J., Viehhauser, G. H. A., Cameron, D., Wildt, M. A., Veloso, F., Joshi, K. D., Dervan, P., Tashiro, T., Davidek, T., Debenedetti, C., Pizio, C., Korotkov, V. A., Liang, Z., Jon-And, K., Ozcan,

2015

Overview

Measurements of the ZZ and WW final states in the mass range above the 2 m Z and 2 m 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 Z Z → 4 ℓ , Z Z → 2 ℓ 2 ν and W W → e ν μ ν 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 C L 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 g g → Z Z and g g → W W 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 Γ H / Γ H 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 g g → V V 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.

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V,Springer Verlag (Germany)
• Subject: 8000 GeV-cms / Astronomy / Astrophysics and Cosmology / background / CERN LHC Coll / Confidence intervals / Coupling / dilepton: mass spectrum / Elementary Particles / Engineering (miscellaneous) / Engineering (miscellaneous); Physics and Astronomy (miscellaneous) / experimental results / gluon gluon: fusion / Hadrons / Heavy Ions / Higgs bosons / Higgs particle: coupling / Higgs particle: decay modes / Higgs particle: hadroproduction / Higgs particle: off-shell / Higgs particle: width / High Energy Physics - Experiment / higher-order / info:eu-repo/classification/ddc/530 / Luminosity / mass spectrum: (4lepton) / Measurement Science and Instrumentation / Nuclear Energy / Nuclear Physics / p p: colliding beams / p p: scattering / Physics / Physics and Astronomy / Physics and Astronomy (miscellaneous) / Physics and Astronomy (miscellaneous); ATLAS; LHC; Higgs Particle / Physics and Astronomy (miscellaneous); Engineering (miscellaneous) / Quantum chromodynamics / quantum chromodynamics: correction / Quantum Field Theories / Quantum Field Theory / Regular - Experimental Physics / Regular Article - Experimental Physics / Settore FIS/01 - FISICA SPERIMENTALE / Signal strength / String Theory / Texts / transverse energy: missing-energy / upper limit / vector boson: leptonic decay / vector boson: pair production / Yield strength