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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.

Combined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the $H\\rightarrow \\gamma \\gamma ,\\, ZZ^*,\\, WW^*,\\, Z\\gamma ,\\, b\\bar{b},\\, \\tau \\tau $ and $\\mu \\mu $ decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 $\\mathrm {fb}^{-1}$ at $\\sqrt{s}=7$ TeV and 20.3 $\\mathrm {fb}^{-1}$ at $\\sqrt{s}=8$ TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is $1.18^{+0.15-0.14}$ . The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and on the Standard Model particle content in loop processes. The data are found to be compatible with the Standard Model expectations for a Higgs boson at a mass of 125.36 GeV for all models considered.

Properties of the Higgs boson are measured in the H → ZZ → 4ℓ (ℓ = e, μ) decay channel. A data sample of proton-proton collisions at $ \\sqrt{s}=13 $ TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb$^{−1}$ is used. The signal strength modifier μ, defined as the ratio of the observed Higgs boson rate in the H → ZZ → 4ℓ decay channel to the standard model expectation, is measured to be μ = 1.05$_{− 0.17}^{+ 0.19}$ at m$_{H}$ = 125.09 GeV, the combined ATLAS and CMS measurement of the Higgs boson mass. The signal strength modifiers for the individual Higgs boson production modes are also measured. The cross section in the fiducial phase space defined by the requirements on lepton kinematics and event topology is measured to be 2. 92$_{− 0.44}^{+ 0.48}$ (stat)$_{− 0.24}^{+ 0.28}$ (syst)fb, which is compatible with the standard model prediction of 2.76 ± 0.14 fb. Differential cross sections are reported as a function of the transverse momentum of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet. The Higgs boson mass is measured to be m$_{H}$ = 125.26 ± 0.21 GeV and the width is constrained using the on-shell invariant mass distribution to be Γ$_{H}$ < 1.10 GeV, at 95% confidence level.

The Compact Linear Collider (CLIC) is an option for a future ${\\mathrm{e}^{+}}{\\mathrm{e}^{-}} $ collider operating at centre-of-mass energies up to $3\\,\\text {TeV} $ , providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: $\\sqrt{s} = 350\\,\\text {GeV} $ , 1.4 and $3\\,\\text {TeV} $ . The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung ( ${\\mathrm{e}^{+}}{\\mathrm{e}^{-}} \\rightarrow {\\mathrm{Z}} {\\mathrm{H}} $ ) and ${\\mathrm{W}} {\\mathrm{W}} $ -fusion ( ${\\mathrm{e}^{+}}{\\mathrm{e}^{-}} \\rightarrow {\\mathrm{H}} {{\\nu }}_{\\!\\mathrm{e}} {\\bar{{\\nu }}}_{\\!\\mathrm{e}} $ ), resulting in precise measurements of the production cross sections, the Higgs total decay width $\\varGamma _{{\\mathrm{H}}}$ , and model-independent determinations of the Higgs couplings. Operation at $\\sqrt{s} > 1\\,\\text {TeV} $ provides high-statistics samples of Higgs bosons produced through ${\\mathrm{W}} {\\mathrm{W}} $ -fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes ${\\mathrm{e}^{+}}{\\mathrm{e}^{-}} \\rightarrow \\mathrm{t} {\\bar{\\mathrm{t}}} {\\mathrm{H}} $ and ${\\mathrm{e}^{+}}{\\mathrm{e}^{-}} \\rightarrow {\\mathrm{H}} {\\mathrm{H}} {{\\nu }}_{\\!\\mathrm{e}} {\\bar{{\\nu }}}_{\\!\\mathrm{e}} $ allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.

The standard model Higgs boson has various decay modes, some of which have been measured in the CMS and ATLAS experiments, located at the Large Hadron Collider at CERN. This paper, calculates the decay of the standard model Higgs boson into D ∗ ± meson through the mechanism direct fragmentation. In this approach, the Higgs boson, first decays into c c ¯ and b b ¯ pairs, and then the heavy quarks fragment directly into D ∗ ± meson. The branching ratios of the SM Higgs boson into D ∗ ± meson have been calculated by considering NLO and NNLO corrections in the fragmentation functions of D ∗ ± .

Decay channels of the Higgs bosons H → A f ¯ , A → hf f ¯ , H ± → Hf f ¯ ' , H ± → h A f f ¯ ' have been investigated within the framework of the Minimal Supersymmetric Standard Model. Analytical expressions for the decay widths have been obtained and their dependence on the masses of the Higgs bosons is examined.

Within the framework of the Minimal Supersymmetric Standard Model, decay channels of Higgs bosons ( h , A ), H ± into arbitrarily polarized fermion-antifermion pairs H h A → ff ¯ , H + → ff ¯ ′ have been investigated. Analytical expressions for the probabilities of the corresponding decays are obtained and their dependence on the mass of the Higgs bosons is investigated.

A search is presented for single production of heavy vector-like quarks (B) that decay to a Higgs boson and a b quark, with the Higgs boson decaying to a highly boosted $ \\mathrm{b}\\overline{\\mathrm{b}} $ pair reconstructed as a single collimated jet. The analysis is based on data collected by the CMS experiment in proton-proton collisions at $ \\sqrt{s}=13 $ TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. The data are consistent with background expectations, and upper limits at 95% confidence level on the product of the B quark cross section and the branching fraction are obtained in the range 1.28–0.07 pb, for a narrow B quark with a mass between 700 and 1800 GeV. The production of B quarks with widths of 10, 20 and 30% of the resonance mass is also considered, and the sensitivities obtained are similar to those achieved in the narrow width case. This is the first search at the CERN LHC for the single production of a B quark through its fully hadronic decay channel, and the first study considering finite resonance widths of the B quark.

A search is performed for electroweak production of a vector-like top quark partner T of charge 2/3 in association with a top or bottom quark, using proton-proton collision data at s√ = 13 TeV collected by the CMS experiment at the LHC in 2016. The data sample corresponds to an integrated luminosity of 35.9 fb−1. The search targets T quarks over a wide range of masses and fractional widths, decaying to a top quark and either a Higgs boson or a Z boson in fully hadronic final states. The search is performed using two experimentally distinct signatures that depend on whether or not each quark from the decays of the top quark, Higgs boson, or Z boson produces an individual resolved jet. Jet substructure, b tagging, and kinematic variables are used to identify the top quark and boson jets, and also to suppress the standard model backgrounds. The data are found to be consistent with the expected backgrounds. Upper limits at 95% confidence level are set on the cross sections for T quark-mediated production of tHQq, tZQq, and their sum, where Q is the associated top or bottom heavy quark and q is another associated quark. The limits are given for each search signature for various T quark widths up to 30% of the T quark mass, and are between 2 pb and 20 fb for T quark masses in the range 0.6–2.6 TeV. These results are significantly more sensitive than prior searches for electroweak single production of T → tH and represent the first constraints on T → tZ using hadronic decays of the Z boson with this production mode.