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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.

A bstract We describe the calculation of all planar master integrals that are needed for the computation of NNLO QCD corrections to the production of two off-shell vector bosons in hadron collisions. The most complicated representatives of integrals in this class are the two-loop four-point functions where two external lines are on the light-cone and two other external lines have different invariant masses. We compute these and other relevant integrals analytically using differential equations in external kinematic variables and express our results in terms of Goncharov polylogarithms. The case of two equal off-shellnesses, recently considered in ref. [ 1 ], appears as a particular case of our general solution.

A search is presented for new massive resonances decaying to WW, WZ or ZZ bosons in $ \\ell \\nu q\\overline{q} $ and $ q\\overline{q}q\\overline{q} $ final states. Results are based on data corresponding to an integrated luminosity of 2.3-2.7 fb$^{−1}$ recorded in proton-proton collisions at $ \\sqrt{s}=13 $ TeV with the CMS detector at the LHC. Decays of spin-1 and spin-2 resonances into two vector bosons are sought in the mass range 0.6-4.0 TeV. No significant excess over the standard model background is observed. Combining the results of the $ \\ell \\nu q\\overline{q} $ and $ q\\overline{q}q\\overline{q} $ final states, cross section and mass exclusion limits are set for models that predict heavy spin-1 and spin-2 resonances. This is the first search for a narrow-width spin-2 resonance at $ \\sqrt{s}=13 $ TeV.

A search for a new heavy particle decaying to a pair of vector bosons (WW or WZ) is presented using data from the CMS detector corresponding to an integrated luminosity of 35.9 fb$^{−1}$ collected in proton-proton collisions at a centre-of-mass energy of 13 TeV in 2016. One of the bosons is required to be a W boson decaying to $eν$ or $μν$, while the other boson is required to be reconstructed as a single massive jet with substructure compatible with that of a highly-energetic quark pair from a W or Z boson decay. The search is performed in the resonance mass range between 1.0 and 4.4 TeV. The largest deviation from the background-only hypothesis is observed for a mass near 1.4 TeV and corresponds to a local significance of 2.5 standard deviations. The result is interpreted as an upper bound on the resonance production cross section. Comparing the excluded cross section values and the expectations from theoretical calculations in the bulk graviton and heavy vector triplet models, spin-2 WW resonances with mass smaller than 1.07 TeV and spin-1 WZ resonances lighter than 3.05 TeV, respectively, are excluded at 95% confidence level.

Studies of the spin, parity and tensor couplings of the Higgs boson in the $H \\rightarrow ZZ^{*} \\rightarrow 4 \\ell $ , $H \\rightarrow WW^{*} \\rightarrow e \\nu \\mu \\nu $ and $H \\rightarrow \\gamma \\gamma $ decay processes at the LHC are presented. The investigations are based on $25\\,\\mathrm{fb}^{-1}$ of pp collision data collected by the ATLAS experiment at $\\sqrt{s}=7$ TeV and $\\sqrt{s}=8$ TeV. The Standard Model (SM) Higgs boson hypothesis, corresponding to the quantum numbers $J^{P}=0^{+}$ , is tested against several alternative spin scenarios, including non-SM spin-0 and spin-2 models with universal and non-universal couplings to fermions and vector bosons. All tested alternative models are excluded in favour of the SM Higgs boson hypothesis at more than 99.9 % confidence level. Using the $H \\rightarrow ZZ^{*} \\rightarrow 4 \\ell $ and $H \\rightarrow WW^{*} \\rightarrow e \\nu \\mu \\nu $ decays, the tensor structure of the interaction between the spin-0 boson and the SM vector bosons is also investigated. The observed distributions of variables sensitive to the non-SM tensor couplings are compatible with the SM predictions and constraints on the non-SM couplings are derived.

A bstract This paper presents the measurement of fiducial and differential cross sections for both the inclusive and electroweak production of a same-sign W -boson pair in association with two jets ( W ± W ± jj ) using 139 fb − 1 of proton-proton collision data recorded at a centre-of-mass energy of s = 13 TeV by the ATLAS detector at the Large Hadron Collider. The analysis is performed by selecting two same-charge leptons, electron or muon, and at least two jets with large invariant mass and a large rapidity difference. The measured fiducial cross sections for electroweak and inclusive W ± W ± jj production are 2.92 ± 0.22 (stat.) ± 0.19 (syst.) fb and 3.38 ± 0.22 (stat.) ± 0.19 (syst.) fb, respectively, in agreement with Standard Model predictions. The measurements are used to constrain anomalous quartic gauge couplings by extracting 95% confidence level intervals on dimension-8 operators. A search for doubly charged Higgs bosons H ±± that are produced in vector-boson fusion processes and decay into a same-sign W boson pair is performed. The largest deviation from the Standard Model occurs for an H ±± mass near 450 GeV, with a global significance of 2.5 standard deviations.

A bstract A search for Higgs boson pair (HH) production in association with a vector boson V (W or Z boson) is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb − 1 . Both hadronic and leptonic decays of V bosons are used. The leptons considered are electrons, muons, and neutrinos. The HH production is searched for in the b b ¯ b b ¯ decay channel. An observed (expected) upper limit at 95% confidence level of VHH production cross section is set at 294 (124) times the standard model prediction. Constraints are also set on the modifiers of the Higgs boson trilinear self-coupling, k λ , assuming k 2V = 1, and vice versa on the coupling of two Higgs bosons with two vector bosons, k 2V . The observed (expected) 95% confidence intervals of these coupling modifiers are − 37.7 < k λ < 37.2 ( − 30.1 < k λ < 28.9) and − 12.2 < k 2V < 13.5 ( − 7.2 < k 2V < 8.9), respectively.