80 research outputs found

    Light Higgs Studies for the CLIC CDR

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    The Higgs boson is the most anticipated discovery at the LHC, which can only partially explore its true nature. Thus one of the most compelling arguments to build a future linear collider is to investigate properties of the Higgs boson, especially to test the predicted linear dependence of the branching ratios on the mass of the final state. At a 3TeV CLIC machine the Higgs boson production cross section is relatively large and allows for a precision measurement of the Higgs branching ratio to pairs of b and c quarks, and even to muons. The cross section times branching ratio of the decays HbbˉH\rightarrow b\bar{b}, HccˉH\rightarrow c\bar{c} and Hμ+μH\rightarrow \mu^{+}\mu^{-} can be measured with a statistical uncertainty of approximately 0.22%, 3.2% and 15%, respectively

    Measurement of the Cross Section Times Branching Ratio of Light Higgs Decays at CLIC

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    The investigation of the properties of a Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state, is currently one of the most compelling arguments for building a linear collider. We demonstrate that the large Higgs boson production cross section at a 3 TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H \rightarrow b^{-}b, H \rightarrow cc^{-} and H \rightarrow {\mu}{\mu} can be measured with a statistical uncertainty of 0.22%, 3.2% and 15%, respectively.Comment: LCWS 2011 Proceeding

    Prospects for the Measurement of the Higgs Yukawa Couplings to b and c quarks, and muons at CLIC

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    The investigation of the properties of the Higgs boson, especially a test of the predicted linear dependence of the branching ratios on the mass of the final state is going to be an integral part of the physics program at colliders at the energy frontier for the foreseeable future. The large Higgs boson production cross section at a 3TeV CLIC machine allows for a precision measurement of the Higgs branching ratios. The cross section times branching ratio of the decays H->bb, H->cc and H->{\mu}{\mu} of a Standard Model Higgs boson with a mass of 120 GeV can be measured with a statistical uncertainty of 0.23%, 3.1% and 15%, respectively, assuming an integrated luminosity of 2 ab-1.Comment: 6 pages, 4 figure

    Prospects of measuring quantum entanglement in ττ final states at a future e+e− Higgs factory

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    We introduce a method to study quantum entanglement at a future e+e− Higgs factory (here the Future Circular Collider colliding e+ and e− (FCC- ee) operating at √s = 240 GeV) in the ττ final state. This method is focused on the τ → πντ decay. We show how the introduced method works on simulated events without detector effects. When detector effects are applied, the necessary τ four-momenta can be reconstructed from kinematic constraints. We will discuss the advantages of e+e− collisions over pp collisions where the reconstruction of the ττ rest frame is more difficult. This discussion will focus on the influence of pT trigger cuts on the visible π± in the τ lepton decay

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    The Compact Linear Collider (CLIC) - 2018 Summary Report

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    Measurement of the total cross section and ρ -parameter from elastic scattering in pp collisions at √s=13 TeV with the ATLAS detector

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    In a special run of the LHC with β⋆=2.5 km, proton–proton elastic-scattering events were recorded at s√=13 TeV with an integrated luminosity of 340 μb−1 using the ALFA subdetector of ATLAS in 2016. The elastic cross section was measured differentially in the Mandelstam t variable in the range from −t=2.5⋅10−4 GeV2 to −t=0.46 GeV2 using 6.9 million elastic-scattering candidates. This paper presents measurements of the total cross section σtot, parameters of the nuclear slope, and the ρ-parameter defined as the ratio of the real part to the imaginary part of the elastic-scattering amplitude in the limit t→0. These parameters are determined from a fit to the differential elastic cross section using the optical theorem and different parameterizations of the t-dependence. The results for σtot and ρ are σtot(pp→X)=104.7±1.1 mb ,ρ=0.098±0.011. The uncertainty in σtot is dominated by the luminosity measurement, and in ρ by imperfect knowledge of the detector alignment and by modelling of the nuclear amplitude.publishedVersio

    Measurement of jet fragmentation in Pb+Pb and pppp collisions at sNN=2.76\sqrt{{s_\mathrm{NN}}} = 2.76 TeV with the ATLAS detector at the LHC

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