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Abstract A data sample of events from proton-proton collisions with at least two jets, and two isolated same-sign or three or more charged leptons, is studied in a search for signatures of new physics phenomena. The data correspond to an integrated luminosity of $$137{\\,{\\text {fb}}^{-1}} $$ 137fb-1 at a center-of-mass energy of $$13\\,{\\text {TeV}} $$ 13TeV , collected in 2016–2018 by the CMS experiment at the LHC. The search is performed using a total of 168 signal regions defined using several kinematic variables. The properties of the events are found to be consistent with the expectations from standard model processes. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos or squarks for various decay scenarios in the context of supersymmetric models conserving or violating R parity. The observed lower mass limits are as large as $$2.1\\,{\\text {TeV}} $$ 2.1TeV for gluinos and $$0.9\\,{\\text {TeV}} $$ 0.9TeV for top and bottom squarks. To facilitate reinterpretations, model-independent limits are provided in a set of simplified signal regions.

Abstract The standard model (SM) production of four top quarks ($$\\text {t} {}{\\overline{\\text {t}}} \\text {t} {}{\\overline{\\text {t}}} $$ tt¯tt¯ ) in proton–proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016–2018 data taking of the LHC, corresponds to an integrated luminosity of 137$$\\,\\text {fb}^{-1}$$ fb-1 at a center-of-mass energy of 13$$\\,\\text {TeV}$$ TeV . The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the $$\\text {t} {}{\\overline{\\text {t}}} \\text {t} {}{\\overline{\\text {t}}} $$ tt¯tt¯ signal are respectively 2.6 and 2.7 standard deviations, and the $$\\text {t} {}{\\overline{\\text {t}}} \\text {t} {}{\\overline{\\text {t}}} $$ tt¯tt¯ cross section is measured to be $$12.6^{+5.8}_{-5.2}\\,\\text {fb} $$ 12.6-5.2+5.8fb . The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, $$y_{\\text {t}}$$ yt , yielding a limit of $$|y_{\\text {t}}/y_{\\text {t}}^{\\mathrm {SM}} | < 1.7$$ |yt/ytSM|<1.7 at $$95\\%$$ 95% confidence level, where $$y_{\\text {t}}^{\\mathrm {SM}}$$ ytSM is the SM value of $$y_{\\text {t}}$$ yt . They are also used to constrain the oblique parameter of the Higgs boson in an effective field theory framework, $$\\hat{H}<0.12$$ H^<0.12 . Limits are set on the production of a heavy scalar or pseudoscalar boson in Type-II two-Higgs-doublet and simplified dark matter models, with exclusion limits reaching 350–470$$\\,\\text {GeV}$$ GeV and 350–550$$\\,\\text {GeV}$$ GeV for scalar and pseudoscalar bosons, respectively. Upper bounds are also set on couplings of the top quark to new light particles.

Abstract Two related searches for phenomena beyond the standard model (BSM) are performed using events with hadronic jets and significant transverse momentum imbalance. The results are based on a sample of proton–proton collisions at a center-of-mass energy of $$13\\,\\text {Te}\\text {V} $$ 13Te , collected by the CMS experiment at the LHC in 2016–2018 and corresponding to an integrated luminosity of 137$$\\,\\text {fb}^{-1}$$ fb-1 . The first search is inclusive, based on signal regions defined by the hadronic energy in the event, the jet multiplicity, the number of jets identified as originating from bottom quarks, and the value of the kinematic variable $$M_{\\mathrm {T2}}$$ MT2 for events with at least two jets. For events with exactly one jet, the transverse momentum of the jet is used instead. The second search looks in addition for disappearing tracks produced by BSM long-lived charged particles that decay within the volume of the tracking detector. No excess event yield is observed above the predicted standard model background. This is used to constrain a range of BSM models that predict the following: the pair production of gluinos and squarks in the context of supersymmetry models conserving R-parity, with or without intermediate long-lived charginos produced in the decay chain; the resonant production of a colored scalar state decaying to a massive Dirac fermion and a quark; or the pair production of scalar and vector leptoquarks each decaying to a neutrino and a top, bottom, or light-flavor quark. In most of the cases, the results obtained are the most stringent constraints to date.

Abstract Measurements of the fiducial inclusive and differential production cross sections of the Higgs boson in proton-proton collisions at s $$ \\sqrt{s} $$ = 13 TeV are performed using events where the Higgs boson decays into a pair of W bosons that subsequently decay into a final state with an electron, a muon, and a pair of neutrinos. The analysis is based on data collected with the CMS detector at the LHC during 2016–2018, corresponding to an integrated luminosity of 137 fb −1. Production cross sections are measured as a function of the transverse momentum of the Higgs boson and the associated jet multiplicity. The Higgs boson signal is extracted and simultaneously unfolded to correct for selection efficiency and resolution effects using maximum-likelihood fits to the observed distributions in data. The integrated fiducial cross section is measured to be 86.5 ± 9.5 fb, consistent with the Standard Model expectation of 82.5 ± 4.2 fb. No significant deviation from the Standard Model expectations is observed in the differential measurements.

Abstract Measurements of the cross section for the production of top quark pairs in association with a pair of jets from bottom quarks σ t t ¯ b b ¯ $$ \\left({\\sigma}_{\\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{b}\\overline{\\mathrm{b}}}\\right) $$ and in association with a pair of jets from quarks of any flavor or gluons σ t t ¯ jj $$ \\left({\\sigma}_{\\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{jj}}\\right) $$ and their ratio are presented. The data were collected in proton-proton collisions at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.9 fb −1. The measurements are performed in a fiducial phase space and extrapolated to the full phase space, separately for the dilepton and lepton+jets channels, where lepton corresponds to either an electron or a muon. The results of the measurements in the fiducial phase space for the dilepton and lepton+jets channels, respectively, are σ t t ¯ jj $$ {\\sigma}_{\\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{jj}} $$ = 2.36±0.02 (stat)±0.20 (syst) pb and 31.0±0.2 (stat)±2.9 (syst) pb, and for the cross section ratio 0.017 ± 0.001 (stat) ± 0.001 (syst) and 0.020 ± 0.001 (stat) ± 0.001 (syst). The values of σ t t ¯ b b ¯ $$ {\\sigma}_{\\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{b}\\overline{\\mathrm{b}}} $$ are determined from the product of the σ t t ¯ jj $$ {\\sigma}_{\\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{jj}} $$ and the cross section ratio, obtaining, respectively, 0.040±0.002 (stat)±0.005 (syst) pb and 0.62±0.03 (stat)±0.07 (syst) pb. These measurements are the most precise to date and are consistent, within the uncertainties, with the standard model expectations obtained using a matrix element calculation at next-to-leading order in quantum chromodynamics matched to a parton shower.

Abstract Twelve measurements of inclusive cross sections of W ± and Z boson production, performed in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, are compared with perturbative quantum chromodynamics calculations at next-to-next- to-leading order (NNLO) accuracy obtained with the CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 parton distribution functions (PDFs). Data and theory agree well for all PDF sets, taking into account the experimental and theoretical uncertainties. A novel procedure is employed to extract the strong coupling constant at the Z pole mass from a detailed comparison of all the experimental fiducial cross sections to the corresponding NNLO theoretical predictions, yielding α S m Z = 0.1163 − 0.0031 + 0.0024 $$ {\\alpha}_{\\mathrm{S}}\\left({m}_{\\mathrm{Z}}\\right)={0.1163}_{-0.0031}^{+0.0024} $$ (CT14), 0.1072 − 0.0040 + 0.0043 $$ {0.1072}_{-0.0040}^{+0.0043} $$ (HERAPDF2.0), 0.1186 ± 0.0025 (MMHT14), and 0.1147 ± 0.0023 (NNPDF3.0). Using the results obtained with the CT14 and MMHT14 PDFs, which yield the most robust and stable α S(m Z) extractions, a value α S m Z = 0.1175 − 0.0028 + 0.0025 $$ {\\alpha}_{\\mathrm{S}}\\left({m}_{\\mathrm{Z}}\\right)={0.1175}_{-0.0028}^{+0.0025} $$ is determined.

Abstract A search for narrow and broad resonances with masses greater than 1.8 TeV decaying to a pair of jets is presented. The search uses proton-proton collision data at s $$ \\sqrt{s} $$ = 13 TeV collected at the LHC, corresponding to an integrated luminosity of 137 fb −1. The background arising from standard model processes is predicted with the fit method used in previous publications and with a new method. The dijet invariant mass spectrum is well described by both data-driven methods, and no significant evidence for the production of new particles is observed. Model independent upper limits are reported on the production cross sections of narrow resonances, and broad resonances with widths up to 55% of the resonance mass. Limits are presented on the masses of narrow resonances from various models: string resonances, scalar diquarks, axigluons, colorons, excited quarks, color-octet scalars, W′ and Z′ bosons, Randall-Sundrum gravitons, and dark matter mediators. The limits on narrow resonances are improved by 200 to 800 GeV relative to those reported in previous CMS dijet resonance searches. The limits on dark matter mediators are presented as a function of the resonance mass and width, and on the associated coupling strength as a function of the mediator mass. These limits exclude at 95% confidence level a dark matter mediator with a mass of 1.8 TeV and width 1% of its mass or higher, up to one with a mass of 4.8 TeV and a width 45% of its mass or higher.

Abstract A search for lepton flavour violating decays of a neutral non-standard-model Higgs boson in the μτ and eτ decay modes is presented. The search is based on proton-proton collisions at a center of mass energy s $$ \\sqrt{s} $$ = 13 TeV collected with the CMS detector in 2016, corresponding to an integrated luminosity of 35.9 fb −1. The τ leptons are reconstructed in the leptonic and hadronic decay modes. No signal is observed in the mass range 200–900 GeV. At 95% confidence level, the observed (expected) upper limits on the production cross section multiplied by the branching fraction vary from 51.9 (57.4) fb to 1.6 (2.1) fb for the μτ and from 94.1 (91.6) fb to 2.3 (2.3) fb for the eτ decay modes.