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Measurements of differential top quark pair tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] cross sections using events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV containing two oppositely charged leptons are presented. The data were recorded by the CMS experiment at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb−1. The differential cross sections are presented as functions of kinematic observables of the top quarks and their decay products, the tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] system, and the total number of jets in the event. The differential cross sections are defined both with particle-level objects in a fiducial phase space close to that of the detector acceptance and with parton-level top quarks in the full phase space. All results are compared with standard model predictions from Monte Carlo simulations with next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD) at matrix-element level interfaced to parton-shower simulations. Where possible, parton-level results are compared to calculations with beyond-NLO precision in QCD. Significant disagreement is observed between data and all predictions for several observables. The measurements are used to constrain the top quark chromomagnetic dipole moment in an effective field theory framework at NLO in QCD and to extract tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] and leptonic charge asymmetries.

A search is presented for the associated production of a standard model Higgs boson with a top quark-antiquark pair (tt¯H\\[ \\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{H} \\]), in which the Higgs boson decays into a b quark-antiquark pair, in proton-proton collisions at a centre-of-mass energy s=13\\[ \\sqrt{s}=13 \\] TeV. The data correspond to an integrated luminosity of 35.9 fb−1 recorded with the CMS detector at the CERN LHC. Candidate tt¯H\\[ \\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{H} \\] events are selected that contain either one or two electrons or muons from the tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] decays and are categorised according to the number of jets. Multivariate techniques are employed to further classify the events and eventually discriminate between signal and background. The results are characterised by an observed tt¯H\\[ \\mathrm{t}\\overline{\\mathrm{t}}\\mathrm{H} \\] signal strength relative to the standard model cross section, μ = σ/σSM, under the assumption of a Higgs boson mass of 125 GeV. A combined fit of multivariate discriminant distributions in all categories results in an observed (expected) upper limit on μ of 1.5 (0.9) at 95% confidence level, and a best fit value of 0.72 ± 0.24(stat) ± 0.38(syst), corresponding to an observed (expected) signal significance of 1.6 (2.2) standard deviations above the background-only hypothesis.

A search for a heavy resonance decaying into a top quark and antiquark tt¯\\[ \\left(\\mathrm{t}\\overline{\\mathrm{t}}\\right) \\] pair is performed using proton-proton collisions at s=13\\[ \\sqrt{s}=13 \\] TeV. The search uses the data set collected with the CMS detector in 2016, which corresponds to an integrated luminosity of 35.9 fb−1. The analysis considers three exclusive final states and uses reconstruction techniques that are optimized for top quarks with high Lorentz boosts, which requires the use of nonisolated leptons and jet substructure techniques. No significant excess of events relative to the expected yield from standard model processes is observed. Upper limits on the production cross section of heavy resonances decaying to a tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] pair are calculated. Limits are derived for a leptophobic topcolor Z′ resonance with widths of 1, 10, and 30%, relative to the mass of the resonance, and exclude masses up to 3.80, 5.25, and 6.65 TeV, respectively. Kaluza-Klein excitations of the gluon in the Randall-Sundrum model are excluded up to 4.55 TeV. To date, these are the most stringent limits on tt¯\\[ \\mathrm{t}\\overline{\\mathrm{t}} \\] resonances.

A search for Higgs bosons that decay into a bottom quark-antiquark pair and are accompanied by at least one additional bottom quark is performed with the CMS detector. The data analyzed were recorded in proton-proton collisions at a centre-of-mass energy of s=13 TeV at the LHC, corresponding to an integrated luminosity of 35.7 fb−1. The final state considered in this analysis is particularly sensitive to signatures of a Higgs sector beyond the standard model, as predicted in the generic class of two Higgs doublet models (2HDMs). No signal above the standard model background expectation is observed. Stringent upper limits on the cross section times branching fraction are set for Higgs bosons with masses up to 1300 GeV. The results are interpreted within several MSSM and 2HDM scenarios.

Normalized differential cross sections for top quark pair production are measured in the dilepton (e+e−, μ+μ−, and μ∓e±) decay channels in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurements are performed with data corresponding to an integrated luminosity of 2.1 fb−1 using the CMS detector at the LHC. The cross sections are measured differentially as a function of the kinematic properties of the leptons, jets from bottom quark hadronization, top quarks, and top quark pairs at the particle and parton levels. The results are compared to several Monte Carlo generators that implement calculations up to next-to-leading order in perturbative quantum chromodynamics interfaced with parton showering, and also to fixed-order theoretical calculations of top quark pair production up to next-to-next-to-leading order.

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract Azimuthal dihadron correlations of charged particles have been measured in PbPb collisions at ...=2.76TeV by the CMS collaboration, using data from the 2011 LHC heavy-ion run. The data set includes a sample of ultra-central (0-0.2% centrality) PbPb events collected using a trigger based on total transverse energy in the hadron forward calorimeters and the total multiplicity of pixel clusters in the silicon pixel tracker. A total of about 1.8 million ultra-central events were recorded, corresponding to an integrated luminosity of 120 [mu]b-1. The observed correlations in ultra-central PbPb events are expected to be particularly sensitive to initial-state fluctuations. The single-particle anisotropy Fourier harmonics, from v ^sub 2^ to v ^sub 6^, are extracted as a function of particle transverse momentum. At higher transverse momentum, the v ^sub 2^ harmonic becomes significantly smaller than the higher-order v ^sub n^ (n[greater than or equal to]3). The p ^sub T^-averaged v ^sub 2^ and v ^sub 3^ are found to be equal within 2%, while higher-order v ^sub n^ decrease as n increases. The breakdown of factorization of dihadron correlations into single-particle azimuthal anisotropies is observed. This effect is found to be most prominent in the ultra-central PbPb collisions, where the initial-state fluctuations play a dominant role. A comparison of the factorization data to hydrodynamic predictions with event-by-event fluctuating initial conditions is also presented. [Figure not available: see fulltext.]

The cross section of top quark–antiquark pair production in proton–proton collisions at s=13TeV is measured by the CMS experiment at the LHC, using data corresponding to an integrated luminosity of 2.2fb-1. The measurement is performed by analyzing events in which the final state includes one electron, one muon, and two or more jets, at least one of which is identified as originating from hadronization of a b quark. The measured cross section is 815±9(stat)±38(syst)±19(lumi) pb, in agreement with the expectation from the standard model.

Results of a search for nonresonant production of Higgs boson pairs, with each Higgs boson decaying to a bb¯\\[ \\mathrm{b}\\overline{\\mathrm{b}} \\] pair, are presented. This search uses data from proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb−1, collected by the CMS detector at the LHC. No signal is observed, and a 95% confidence level upper limit of 847 fb is set on the cross section for standard model nonresonant Higgs boson pair production times the squared branching fraction of the Higgs boson decay to a bb¯\\[ \\mathrm{b}\\overline{\\mathrm{b}} \\] pair. The same signature is studied, and upper limits are set, in the context of models of physics beyond the standard model that predict modified couplings of the Higgs boson.

Abstract A search is reported for massive resonances decaying into a quark and a vector boson (W or Z), or two vector bosons (WW, WZ, or ZZ). The analysis is performed on an inclusive sample of multijet events corresponding to an integrated luminosity of 19.7 fb-1, collected in proton-proton collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. The search uses novel jet-substructure identification techniques that provide sensitivity to the presence of highly boosted vector bosons decaying into a pair of quarks. Exclusion limits are set at a confidence level of 95% on the production of: (i) excited quark resonances q *decaying to qW and qZ for masses less than 3.2 TeV and 2.9 TeV, respectively, (ii) a Randall-Sundrum graviton GRS decaying into WW for masses below 1.2 TeV, and (iii) a heavy partner of the W boson W' decaying into WZ for masses less than 1.7 TeV. For the first time mass limits are set on W' [arrow right] WZ and GRS [arrow right] WW in the all-jets final state. The mass limits on q* [arrow right] qW, q* [arrow right] qZ, W' [arrow right] WZ, GRS [arrow right] WW are the most stringent to date. A model with a \"bulk\" graviton Gbulk that decays into WW or ZZ bosons is also studied. [Figure not available: see fulltext.]

The top quark pair production cross section σtt¯ is measured for the first time in pp collisions at a center-of-mass energy of 5.02 TeV. The data were collected by the CMS experiment at the LHC and correspond to an integrated luminosity of 27.4 pb−1. The measurement is performed by analyzing events with at least one charged lepton. The measured cross section is σtt¯ = 69.5 ± 6.1 (stat) ± 5.6 (syst) ± 1.6 (lumi) pb, with a total relative uncertainty of 12%. The result is in agreement with the expectation from the standard model. The impact of the presented measurement on the determination of the gluon distribution function is investigated.