12 research outputs found

    Search for an excited lepton that decays via a contact interaction to a lepton and two jets in proton-proton collisions at root s=13 TeV

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    Results are presented from a search for events containing an excited lepton (electron or muon) produced in association with an ordinary lepton of the same flavor and decaying to a lepton and two hadronic jets. Both the production and the decay of the excited leptons are assumed to occur via a contact interaction with a characteristic energy scale ?. The branching fraction for the decay mode under study increases with the mass of the excited lepton and is the most sensitive channel for very heavy excited leptons. The analysis uses a sample of proton-proton collisions collected by the CMS experiment at the LHC at root s = 13 TeV, corresponding to an integrated luminosity of 77.4 fb(-1). The four-body invariant mass of the two lepton plus two jet system is used as the primary discriminating variable. No significant excess of events beyond the expectation for standard model processes is observed. Assuming that ? is equal to the mass of the excited leptons, excited electrons and muons with masses below 5.6 and 5.7 TeV, respectively, are excluded at 95% confidence level. These are the best limits to date

    Measurement of the top quark polarization and <tex>t\bar{t}</tex>barspincorrelationsusingdileptonfinalstatesinprotonprotoncollisionsat<tex>s</tex>-barspin correlations using dilepton final states in proton-proton collisions at <tex>\sqrt{s}</tex>=13 TeV

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    Search for long-lived particles using nonprompt jets and missing transverse momentum with proton-proton collisions at root s=13 TeV

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    A search for long-lived particles decaying to displaced, nonprompt jets and missing transverse momentum is presented. The data sample corresponds to an integrated luminosity of 137 fb(-1) of proton-proton collisions at a center-of-mass energy of 13 TeV collected by the CMS experiment at the CERN LHC in 2016-2018. Candidate signal events containing nonprompt jets are identified using the timing capabilities of the CMS electromagnetic calorimeter. The results of the search are consistent with the background prediction and are interpreted using a gauge-mediated supersymmetry breaking reference model with a gluino next-to-lightest supersymmetric particle. In this model, gluino masses up to 2100, 2500, and 1900 GeV are excluded at 95% confidence level for proper decay lengths of 0.3, 1, and 100 m, respectively. These are the best limits to date for such massive gluinos with proper decay lengths greater than similar to 0.5 m. (C) 2019 The Author. Published by Elsevier B.V

    Multiparticle correlation studies in pPb collisions at <tex>\sqrt{s_{NN}}$</tex>=8.16 TeV

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    Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements

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    Measurement of the single top quark and antiquark production cross sections in the t channel and their ratio in proton-proton collisions at <tex>\sqrt{s}$</tex>=13 TeV

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    Measurement of the Y(1S) pair production cross section and search for resonances decaying to <tex>Y(1S)\mu^{+}\mu^{-}$</tex> in proton-proton collisions at 1as=13 TeV

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    Measurement of the Y(1S) pair production cross section and search for resonances decaying to Y(1S)mu(+)mu(-) in proton-proton collisions at root s=13 TeV

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    The fiducial cross section for Y(1S) pair production in proton-proton collisions at a center-of-mass energy of 13TeVin the region where both Y(1S) mesons have an absolute rapidity below 2.0 is measured to be 79 +/- 11 (stat) +/- 6 (syst) +/- 3 (B) pbassuming the mesons are produced unpolarized. The last uncertainty corresponds to the uncertainty in the Y(1S) meson dimuon branching fraction. The measurement is performed in the final state with four muons using proton-proton collision data collected in 2016 by the CMS experiment at the LHC, corresponding to an integrated luminosity of 35.9 fb(-1). This process serves as a standard model reference in a search for narrow resonances decaying to Y(1S)mu(+)mu(-) in the same final state. Such a resonance could indicate the existence of a tetraquark that is a bound state of two bquarks and two (b) over bar antiquarks. The tetraquark search is performed for masses in the vicinity of four times the bottom quark mass, between 17.5 and 19.5 GeV, while a generic search for other resonances is performed for masses between 16.5 and 27 GeV. No significant excess of events compatible with a narrow resonance is observed in the data. Limits on the production cross section times branching fraction to four muons via an intermediate Y(1S) resonance are set as a function of the resonance mass. (C) 2020 The Author(s). Published by Elsevier B.V

    Production of <tex>\varLambda_{c}^{+}</tex>baryonsinprotonprotonandleadleadcollisionsat<tex>sNN</tex> baryons in proton-proton and lead-lead collisions at <tex>\sqrt{s_{NN}}</tex>=5.02 TeV

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    Study of excited <tex>\Lambda_{b}^{0}</tex>statesdecayingto<tex>Λb0π+π</tex> states decaying to <tex>\Lambda_{b}^{0}\pi^{+}\pi^{-}</tex> in proton-proton collisions at 1as=13TeV

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