1,520 research outputs found

    First Search for Exclusive Diphoton Production at High Mass with Tagged Protons in Proton-Proton Collisions at √s = 13 TeV

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    Search for strongly interacting massive particles generating trackless jets in proton-proton collisions at s = 13 TeV

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    A search for dark matter in the form of strongly interacting massive particles (SIMPs) using the CMS detector at the LHC is presented. The SIMPs would be produced in pairs that manifest themselves as pairs of jets without tracks. The energy fraction of jets carried by charged particles is used as a key discriminator to suppress efficiently the large multijet background, and the remaining background is estimated directly from data. The search is performed using proton-proton collision data corresponding to an integrated luminosity of 16.1 fb - 1 , collected with the CMS detector in 2016. No significant excess of events is observed above the expected background. For the simplified dark matter model under consideration, SIMPs with masses up to 100 GeV are excluded and further sensitivity is explored towards higher masses

    Search for high-mass exclusive γγ → WW and γγ → ZZ production in proton-proton collisions at s \sqrt{s} = 13 TeV

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    Search for WÂŽ bosons decaying to a top and a bottom quark at root s=13 TeV in the hadronic final state

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    A search is performed for W ' bosons decaying to a top and a bottom quark in the all-hadronic final state, in proton-proton collisions at a center-of-mass energy of 13TeV. The analyzed data were collected by the CMS experiment between 2016 and 2018 and correspond to an integrated luminosity of 137fb(-1). Deep neural network algorithms are used to identify the jet initiated by the bottom quark and the jet containing the decay products of the top quark when the W ' boson from the top quark decays hadronically. No excess above the estimated standard model background is observed. Upper limits on the production cross sections of W ' bosons decaying to a top and a bottom quark are set. Both left- and right-handed W ' bosons with masses below 3.4TeV are excluded at 95% confidence level, and the most stringent limits to date on W ' bosons decaying to a top and a bottom quark in the all-hadronic final state are obtained. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe

    Measurement of the top quark Yukawa coupling from tt̄ kinematic distributions in the dilepton final state in proton-proton collisions at √s = 13  TeV

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    A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at √s = 13  TeV, corresponding to an integrated luminosity of 137  fb⁻Âč, recorded with the CMS detector. The coupling strength with respect to the standard model value, Y_t, is determined from kinematic distributions in tt̄ final states containing ee, ΌΌ, or eÎŒ pairs. Variations of the Yukawa coupling strength lead to modified distributions for tt̄ production. In particular, the distributions of the mass of the tt̄ system and the rapidity difference of the top quark and antiquark are sensitive to the value of Y_t. The measurement yields a best fit value of Y_t = 1.16^(+0.24)_(−0.35), bounding Y_t < 1.54 at a 95% confidence level

    Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC

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    The performance is presented of the reconstruction and identification algorithms for electrons and photons with the CMS experiment at the LHC. The reported results are based on proton-proton collision data collected at a center-of-mass energy of 13 TeV and recorded in 2016-2018, corresponding to an integrated luminosity of 136 fb(-1). Results obtained from lead-lead collision data collected at root S-NN = 5.02 TeV are also presented. Innovative techniques are used to reconstruct the electron and photon signals in the detector and to optimize the energy resolution. Events with electrons and photons in the final state are used to measure the energy resolution and energy scale uncertainty in the recorded events. The measured energy resolution for electrons produced in Z boson decays in proton-proton collision data ranges from 2 to 5%, depending on electron pseudorapidity and energy loss through bremsstrahlung in the detector material. The energy scale in the same range of energies is measured with an uncertainty smaller than 0.1 (0.3)% in the barrel (endcap) region in proton-proton collisions and better than 1(3)% in the barrel (endcap) region in heavy ion collisions. The timing resolution for electrons from Z boson decays with the full 2016-2018 proton-proton collision data set is measured to be 200 ps.Peer reviewe

    Measurement of the top quark Yukawa coupling from ttˉ\bar{t} kinematic distributions in the dilepton final state in proton-proton collisions at √s = 13 TeV

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    A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at s\sqrt{s}=13  TeV, corresponding to an integrated luminosity of 137  fb−1^{-1}, recorded with the CMS detector. The coupling strength with respect to the standard model value, Yt_{t}, is determined from kinematic distributions in tt̅ final states containing ee, ΌΌ, or eÎŒ pairs. Variations of the Yukawa coupling strength lead to modified distributions for tt̅ production. In particular, the distributions of the mass of the tt̅ system and the rapidity difference of the top quark and antiquark are sensitive to the value of Yt_{t}. The measurement yields a best fit value of Yt_{t}=1.16+0.24−0.35, bounding Yt_{t}<1.54 at a 95% confidence level

    Search for a heavy vector resonance decaying to a Z{\mathrm{Z}}_{\mathrm{}}^{\mathrm{}} boson and a Higgs boson in proton-proton collisions at s=13 TeV\sqrt{s} = 13\,\text {Te}\text {V}

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    Study of Drell-Yan dimuon production in proton-lead collisions at sNN \sqrt{s_{\mathrm{NN}}} = 8.16 TeV

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    Differential cross sections for the Drell-Yan process, including Z boson production, using the dimuon decay channel are measured in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of 8.16 TeV. A data sample recorded with the CMS detector at the LHC is used, corresponding to an integrated luminosity of 173 nb−1. The differential cross section as a function of the dimuon mass is measured in the range 15–600 GeV, for the first time in proton-nucleus collisions. It is also reported as a function of dimuon rapidity over the mass ranges 15–60 GeV and 60–120 GeV, and ratios for the p-going over the Pb-going beam directions are built. In both mass ranges, the differential cross sections as functions of the dimuon transverse momentum pT and of a geometric variable ϕ* are measured, where ϕ* highly correlates with pT but is determined with higher precision. In the Z mass region, the rapidity dependence of the data indicate a modification of the distribution of partons within a lead nucleus as compared to the proton case. The data are more precise than predictions based upon current models of parton distributions
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