77 research outputs found

    Search for the Z Boson Decay to ττμμ in Proton-Proton Collisions at √s = 13 TeV

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    The first search for the boson decay to ⁢⁢⁢ at the CERN LHC is presented, based on data collected by the CMS experiment at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138  fb−1. The data are compatible with the predicted background. For the first time, an upper limit at the 95% confidence level of 6.9 times the standard model expectation is placed on the ratio of the →⁢⁢⁢ to →4⁢ branching fractions. Limits are also placed on the six flavor-conserving four-lepton effective-field-theory operators involving two muons and two tau leptons, for the first time testing all such operators

    Measurement of the polarizations of prompt and non-prompt J/ψ and ψ (2S) mesons produced in pp collisions at s\sqrt{s} = 13 TeV

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    The polarizations of prompt and non-prompt J∕ψ and ψ(2S) mesons are measured in proton-proton collisions at √ = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb1^{−1}. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, , is measured as a function of the transverse momentum, T_T, of the charmonium states, in the 25–120 and 20–100 GeV ranges for the J∕ψ and ψ(2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for T ≳ 25 GeV, the non-prompt J∕ψ and ψ(2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for T_T exceeding 30 times the J∕ψ mass, where tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at √ = 7 TeV, the prompt polarizations show a significant variation with T_T, at low T_T

    Search for Soft Unclustered Energy Patterns in Proton-Proton Collisions at 13 TeV

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    he first search for soft unclustered energy patterns (SUEPs) is performed using an integrated luminosity of 138  fb−1 of proton-proton collision data at √=13  TeV, collected in 2016–2018 by the CMS detector at the LHC. Such SUEPs are predicted by hidden valley models with a new, confining force with a large ’t Hooft coupling. In events with boosted topologies, selected by high-threshold hadronic triggers, the multiplicity and sphericity of clustered tracks are used to reject the background from standard model quantum chromodynamics. With no observed excess of events over the standard model expectation, limits are set on the cross section for production via gluon fusion of a scalar mediator with SUEP-like decays

    Observation of the J / ψ → μ⁺ μ⁻ μ⁺ μ⁻ decay in proton-proton collisions at √s = 13 TeV

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    Search for new physics in high-mass diphoton events from proton-proton collisions at s \sqrt{\textrm{s}} = 13 TeV

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    Search for a resonance decaying to a W boson and a photon in proton-proton collisions at s \sqrt{s} = 13 TeV using leptonic W boson decays

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    A search for a new charged particle X with mass between 0.3 and 2.0 TeV decaying to a W boson and a photon is presented, using proton-proton collision data at a center-of-mass energy of 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb−1. Particle X has electric charge ±1 and is assumed to have spin 0. The search is performed using the electron and muon decays of the W boson. No significant excess above the predicted background is observed. The upper limit at 95% confidence level on the product of the production cross section of the X and its branching fraction to a W boson and a photon is found to be 94 (137) fb for a 0.3 TeV resonance and 0.75 (0.81) fb for a 2.0 TeV resonance, for an X width-to-mass ratio of 0.01% (5%). This search presents the most stringent constraints to date on the existence of such resonances across the probed mass range. A statistical combination with an earlier study based on the hadronic decay mode of the W boson is also performed, and the upper limit at 95% confidence level for a 2.0 TeV resonance is reduced to 0.50 (0.63) fb for an X width-to-mass ratio of 0.01% (5%)

    Search for a heavy resonance decaying into a Z and a Higgs boson in events with an energetic jet and two electrons, two muons, or missing transverse momentum in proton-proton collisions at s \sqrt{s} = 13 TeV

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    A search is presented for a heavy resonance decaying into a Z boson and a Higgs (H) boson. The analysis is based on data from proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb−1, recorded with the CMS experiment in the years 2016–2018. Resonance masses between 1.4 and 5 TeV are considered, resulting in large transverse momenta of the Z and H bosons. Final states that result from Z boson decays to pairs of electrons, muons, or neutrinos are considered. The H boson is reconstructed as a single large-radius jet, recoiling against the Z boson. Machine-learning flavour-tagging techniques are employed to identify decays of a Lorentz-boosted H boson into pairs of charm or bottom quarks, or into four quarks via the intermediate H → WW* and ZZ* decays. The analysis targets H boson decays that were not generally included in previous searches using the H → channel. Compared with previous analyses, the sensitivity for high resonance masses is improved significantly in the channel where at most one b quark is tagged

    Measurement of the Bs0J/ψKS0 {\textrm{B}}_{\textrm{s}}^0\to \textrm{J}/{ψ\textrm{K}}_{\textrm{S}}^0 effective lifetime from proton-proton collisions at s \sqrt{s} = 13 TeV

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    Measurements of inclusive and differential cross sections for top quark production in association with a Z boson in proton-proton collisions at s \sqrt{s} = 13 TeV

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    Measurement of inclusive and differential cross sections of single top quark production in association with a W boson in proton-proton collisions at s \sqrt{s} = 13.6 TeV

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