152 research outputs found

    Measurement of the Higgs boson width and evidence of its off-shell contributions to ZZ production

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    Since the discovery of the Higgs boson in 2012, detailed studies of its properties have been ongoing. Besides its mass, its width—related to its lifetime—is an important parameter. One way to determine this quantity is to measure its off-shell production, where the Higgs boson mass is far away from its nominal value, and relating it to its on-shell production, where the mass is close to the nominal value. Here we report evidence for such off-shell contributions to the production cross-section of two Z bosons with data from the CMS experiment at the CERN Large Hadron Collider. We constrain the total rate of the off-shell Higgs boson contribution beyond the Z boson pair production threshold, relative to its standard model expectation, to the interval [0.0061, 2.0] at the 95% confidence level. The scenario with no off-shell contribution is excluded at a p-value of 0.0003 (3.6 standard deviations). We measure the width of the Higgs boson as Γ\GammaH_H=3.21.7+2.4^{+2.4}_{−1.7}MeV, in agreement with the standard model expectation of 4.1 MeV. In addition, we set constraints on anomalous Higgs boson couplings to W and Z boson pairs

    Precision measurement of the W boson decay branching fractions in proton-proton collisions at ? s=13 TeV

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    The leptonic and inclusive hadronic decay branching fractions of the W boson are measured using proton-proton collision data collected at √ s = 13     TeV by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 35.9     fb − 1 . Events characterized by the production of one or two W bosons are selected and categorized based on the multiplicity and flavor of reconstructed leptons, the number of jets, and the number of jets identified as originating from the hadronization of b quarks. A binned maximum likelihood estimate of the W boson branching fractions is performed simultaneously in each event category. The measured branching fractions of the W boson decaying into electron, muon, and tau lepton final states are ( 10.83 ± 0.10 ) % , ( 10.94 ± 0.08 ) % , and ( 10.77 ± 0.21 ) % , respectively, consistent with lepton flavor universality for the weak interaction. The average leptonic and inclusive hadronic decay branching fractions are estimated to be ( 10.89 ± 0.08 ) % and ( 67.32 ± 0.23 ) % , respectively. Based on the hadronic branching fraction, three standard model quantities are subsequently derived: the sum of squared elements in the first two rows of the Cabibbo–Kobayashi–Maskawa (CKM) matrix ∑ i j | V i j | 2 = 1.984 ± 0.021 , the CKM element | V c s | = 0.967 ± 0.011 , and the strong coupling constant at the W boson mass scale, α S ( m 2 W ) = 0.095 ± 0.033

    Measurement of the Inclusive and Differential Higgs Boson Production Cross Sections in the Decay Mode to a Pair of τ Leptons in pp Collisions at s =13 TeV

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    Copyright © 2022 CERN, for the CMS Collaboration. Measurements of the inclusive and differential fiducial cross sections of the Higgs boson are presented, using the τ lepton decay channel. The differential cross sections are measured as functions of the Higgs boson transverse momentum, jet multiplicity, and transverse momentum of the leading jet in the event, if any. The analysis is performed using proton-proton collision data collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb−1. These are the first differential measurements of the Higgs boson cross section in the final state of two τ leptons. In final states with a large jet multiplicity or with a Lorentz-boosted Higgs boson, these measurements constitute a significant improvement over measurements performed in other final states.SCOAP3

    Search for resonances decaying to three W bosons in the hadronic final state in proton-proton collisions at ps=13 TeV

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    A search for Kaluza-Klein excited vector boson resonances, W KK , decaying in cascade to three W bosons via a scalar radion R , W KK → W R → W W W , in a final state containing two or three massive jets is presented. The search is performed with √ s = 13     TeV proton-proton collision data collected by the CMS experiment at the CERN LHC during 2016–2018, corresponding to an integrated luminosity of 138     fb − 1 . Two final states are simultaneously probed, one where the two W bosons produced by the R decay are reconstructed as separate, large-radius, massive jets, and one where they are merged into a single large-radius jet. The observed data are in agreement with the standard model expectations. Limits are set on the product of the W KK resonance cross section and branching fraction to three W bosons in an extended warped extra-dimensional model and are the first of their kind at the LHC

    Measurement of the Higgs boson width and evidence of its off-shell contributions to ZZ production

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    Since the discovery of the Higgs boson in 2012, detailed studies of its properties have been ongoing. Besides its mass, its width—related to its lifetime—is an important parameter. One way to determine this quantity is to measure its off-shell production, where the Higgs boson mass is far away from its nominal value, and relating it to its on-shell production, where the mass is close to the nominal value. Here we report evidence for such off-shell contributions to the production cross-section of two Z bosons with data from the CMS experiment at the CERN Large Hadron Collider. We constrain the total rate of the off-shell Higgs boson contribution beyond the Z boson pair production threshold, relative to its standard model expectation, to the interval [0.0061, 2.0] at the 95% confidence level. The scenario with no off-shell contribution is excluded at a p-value of 0.0003 (3.6 standard deviations). We measure the width of the Higgs boson as ΓH=3.2+2.4−1.7MeV, in agreement with the standard model expectation of 4.1 MeV. In addition, we set constraints on anomalous Higgs boson couplings to W and Z boson pairs

    OPUS I: Grundlagenuntersuchungen zu anwendungsorientierten reflektierenden und transmittierenden UV-Strahlfuehrungs- und Strahlformungsoptiken. Teilvorhaben: Prozess- und maschinentechnische Grundlagenuntersuchungen fuer UV-Strahlfuehrungs- und Strahlformungsoptiken Abschlussbericht

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    The project OPUS I is based on the growing requirement of high-quality UV laser systems and coated optics components of high functionality for laser beam guidance and -shaping. Goal of the subtask at the Fraunhofer IPT were basic studies on process technology and mechanical engineering for UV beam guidance and -shaping optics. Beside the selection of suitable materials and their characterization the optimization of the process was a main task of the project. An increase of the efficiency of UV lasers in precision manufacturing and micro structuring can be achieved by the use of non-rotationally symmetric optics. Such optics cannot be manufactured by conventional manufacturing processes like grinding and polishing with the necessary accuracy. Therefore a Fast Tool Servo system was developed, which enables the manufacturing of non-rotationally symmetric optics by single point diamond turning. The investigations of the manufacturing characteristics of different materials as well as the process optimization provide a broad database for the further use of this technology. This knowledge can be used to estimate the potentials and limitations of the technology. The Fast Tool Servo, which was developed in this project, is a good basis for further developments in the area of high dynamic and accurate tool positioning systems. (orig.)SIGLEAvailable from TIB Hannover: F00B987+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung (BMBF), Bonn (Germany)DEGerman

    Observation of same-sign WW production from double parton scattering in proton-proton collisions at 1as=13 TeV

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    Abstract: The first observation of the production of (WW +/-)-W-+/- bosons from double parton scattering processes using same-sign electron-muon and dimuon events in proton-proton collisions is reported. The data sample corresponds to an integrated luminosity of 138 fb(-1 )recorded at a center-of-mass energy of 13 TeV using the CMS detector at the CERN LHC. Multivariate discriminants are used to distinguish the signal process from the main backgrounds. A binned maximum likelihood fit is performed to extract the signal cross section. The measured cross section for production of same-sign W bosons decaying leptonically is 80.7 +/- 11.2(stat)( -8.6)(+9.5)(syst) +/- 12.1(model) fb, whereas the measured fiducial cross section is 6.28 +/- 0.81(stat) +/- 0.69(syst) +/- 0.37(model) fb. The observed significance of the signal is 6.2 standard deviations above the background-only hypothesis

    Search for electroweak production of charginos and neutralinos in proton-proton collisions at 1as=13 TeV

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    Measurement of the B-s(0) \u2192 mu(+)mu(-) decay properties and search for the B-0 \u2192 mu(+)mu(-) decay in proton-proton collisions at 1as=13 TeV

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    Measurement of differential cross sections for the production of a Z boson in association with jets in proton-proton collisions at 1as=13 TeV

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    Abstract: A measurement is presented of the production of Z bosons that decay into two electrons or muons in association with jets, in proton-proton collisions at a center-of-mass energy of 13 TeV. The data were cross sections are measured as a function of the transverse momentum (pT) of the Z boson and the transverse momentum and rapidities of the five jets with largest pT. The jet multiplicity distribution is measured for up to eight jets. The hadronic activity in the events is estimated using the scalar sum of the pT of all the jets. All measurements are unfolded to the stable-particle level and compared with predictions from various Monte Carlo event generators, as well as with expectations at leading and next-to-leading orders in perturbative quantum chromodynamics
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