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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.

The first measurement of the jet mass [Formula: see text] of top quark jets produced in [Formula: see text] events from pp collisions at [Formula: see text] [Formula: see text] is reported for the jet with the largest transverse momentum [Formula: see text] in highly boosted hadronic top quark decays. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay [Formula: see text] with [Formula: see text] where [Formula: see text] is an electron or muon, are used to select [Formula: see text] events with large Lorentz boosts. The products of the fully hadronic decay [Formula: see text] with [Formula: see text] are reconstructed using a single Cambridge-Aachen jet with distance parameter [Formula: see text], and [Formula: see text] [Formula: see text]. The [Formula: see text] cross section as a function of [Formula: see text] is unfolded at the particle level and is used to test the modelling of highly boosted top quark production. The peak position of the [Formula: see text] distribution is sensitive to the top quark mass [Formula: see text], and the data are used to extract a value of [Formula: see text] to assess this sensitivity.

Normalized double-differential cross sections for top quark pair ([Formula: see text]) production are measured in pp collisions at a centre-of-mass energy of 8[Formula: see text] with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7[Formula: see text]. The measurement is performed in the dilepton [Formula: see text] final state. The [Formula: see text] cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and [Formula: see text] system. The data are compared to calculations using perturbative quantum chromodynamics at next-to-leading and approximate next-to-next-to-leading orders. They are also compared to predictions of Monte Carlo event generators that complement fixed-order computations with parton showers, hadronization, and multiple-parton interactions. Overall agreement is observed with the predictions, which is improved when the latest global sets of proton parton distribution functions are used. The inclusion of the measured [Formula: see text] cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

A measurement of the top quark mass is reported in events containing a single top quark produced via the electroweak channel. The analysis is performed using data from proton-proton collisions collected with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb[Formula: see text]. Top quark candidates are reconstructed from their decay to a [Formula: see text] boson and a b quark, with the [Formula: see text] boson decaying leptonically to a muon and a neutrino. The final state signature and kinematic properties of single top quark events in the channel are used to enhance the purity of the sample, suppressing the contribution from top quark pair production. A fit to the invariant mass distribution of reconstructed top quark candidates yields a value of the top quark mass of [Formula: see text]. This result is in agreement with the current world average, and represents the first measurement of the top quark mass in event topologies not dominated by top quark pair production, therefore contributing to future averages with partially uncorrelated systematic uncertainties and a largely uncorrelated statistical uncertainty.

This paper reports the measurement of [Formula: see text] meson production in proton-proton ([Formula: see text]) and proton-lead ([Formula: see text]) collisions at a center-of-mass energy per nucleon pair of [Formula: see text] by the CMS experiment at the LHC. The data samples used in the analysis correspond to integrated luminosities of 28[Formula: see text] and 35[Formula: see text] for [Formula: see text] and [Formula: see text] collisions, respectively. Prompt and nonprompt [Formula: see text] mesons, the latter produced in the decay of [Formula: see text] hadrons, are measured in their dimuon decay channels. Differential cross sections are measured in the transverse momentum range of [Formula: see text], and center-of-mass rapidity ranges of [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]). The nuclear modification factor, [Formula: see text], is measured as a function of both [Formula: see text] and [Formula: see text]. Small modifications to the [Formula: see text] cross sections are observed in [Formula: see text] relative to [Formula: see text] collisions. The ratio of [Formula: see text] production cross sections in [Formula: see text]-going and Pb-going directions, [Formula: see text], studied as functions of [Formula: see text] and [Formula: see text], shows a significant decrease for increasing transverse energy deposited at large pseudorapidities. These results, which cover a wide kinematic range, provide new insight on the role of cold nuclear matter effects on prompt and nonprompt [Formula: see text] production.

Abstract This paper reports the measurement of $$\\mathrm{J}/{\\psi }$$ J / ψ meson production in proton–proton ( $$\\mathrm {p}\\mathrm {p}$$ p p ) and proton–lead ( $$\\mathrm {p}\\mathrm {Pb}$$ p Pb ) collisions at a center-of-mass energy per nucleon pair of $$5.02\\,\\text {TeV} $$ 5.02 TeV by the CMS experiment at the LHC. The data samples used in the analysis correspond to integrated luminosities of 28 $$\\,\\text {pb}^{-1}$$ pb - 1 and 35 $$\\,\\text {nb}^{-1}$$ nb - 1 for $$\\mathrm {p}\\mathrm {p}$$ p p and $$\\mathrm {p}\\mathrm {Pb}$$ p Pb collisions, respectively. Prompt and nonprompt $$\\mathrm{J}/{\\psi }$$ J / ψ mesons, the latter produced in the decay of $${\\mathrm {B}}$$ B hadrons, are measured in their dimuon decay channels. Differential cross sections are measured in the transverse momentum range of $$2

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