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A bstract A search is presented for additional scalar (H) or pseudoscalar (A) Higgs bosons decaying to a top quark pair in proton-proton collisions at a center-of-mass energy of 13 TeV. The data set analyzed corresponds to an integrated luminosity of 35.9 fb − 1 collected by the CMS experiment at the LHC. Final states with one or two charged leptons are considered. The invariant mass of the reconstructed top quark pair system and variables that are sensitive to the spin of the particles decaying into the top quark pair are used to search for signatures of the H or A bosons. The interference with the standard model top quark pair background is taken into account. A moderate signal-like deviation compatible with an A boson with a mass of 400 GeV is observed with a global significance of 1.9 standard deviations. New stringent constraints are reported on the strength of the coupling of the hypothetical bosons to the top quark, with the mass of the bosons ranging from 400 to 750 GeV and their total relative width from 0.5 to 25%. The results of the search are also interpreted in a minimal supersymmetric standard model scenario. Values of m A from 400 to 700 GeV are probed, and a region with values of tan β below 1.0 to 1.5, depending on m A , is excluded at 95% confidence level.

A bstract Pair production of Y(1S) mesons is observed at the LHC in proton-proton collisions at s = 8 TeV by the CMS experiment in a data sample corresponding to an integrated luminosity of 20.7 fb −1 . Both Y(1S) candidates are fully reconstructed via their decays to μ + μ − . The fiducial acceptance region is defined by an absolute Y(1S) rapidity smaller than 2.0. The fiducial cross section for the production of Y(1S) pairs, assuming that both mesons decay isotropically, is measured to be 68.8±12.7 (stat)±7.4 (syst)±2.8 ( ℬ ) pb, where the third uncertainty comes from the uncertainty in the branching fraction of Y(1S) decays to μ + μ − . Assuming instead that the Y(1S) mesons are produced with different polarizations leads to variations in the measured cross section in the range from −38% to +36%.

The differential cross section and charge asymmetry for inclusive p p → W ± + X → μ ± ν + X production at s = 8 TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8 fb - 1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10 - 3 to 10 - 1 .

A bstract A search for a charged Higgs boson is performed with a data sample corresponding to an integrated luminosity of 19.7 ± 0.5 fb −1 collected with the CMS detector in proton-proton collisions at s = 8 ,TeV. The charged Higgs boson is searched for in top quark decays for m H ± < m t − m b , and in the direct production pp → t(b)H ± for m H ± > m t − m b . The H ± → τ ± ν τ and H ± → tb decay modes in the final states τ h +jets, μτ h , ℓ +jets, and ℓℓ ’ ( ℓ =e, μ ) are considered in the search. No signal is observed and 95% confidence level upper limits are set on the charged Higgs boson production. A model-independent upper limit on the product branching fraction ℬ t → H ± b ℬ H ± → τ ± ν τ = 1.2 − 0.15 % is obtained in the mass range m H ± = 80–160 GeV, while the upper limit on the cross section times branching fraction σ pp → t b H ± ℬ H ± → τ ± ν τ = 0.38 − 0.025 pb is set in the mass range m H + = 180–600 GeV. Here, σ (pp → t(b)H ± ) stands for the cross section sum σ pp → t ¯ b H + + σ pp → t b ¯ H − . Assuming ℬ H ± → t b = 1 , an upper limit on σ (pp → t(b)H ± ) of 2.0–0.13 pb is set for m H ± = 180–600 GeV. The combination of all considered decay modes and final states is used to set exclusion limits in the m H ±−tan β parameter space in different MSSM benchmark scenarios.

The nuclear modification factor R AA and the azimuthal anisotropy coefficient v 2 of prompt and nonprompt (i.e. those from decays of b hadrons) J / ψ mesons, measured from PbPb and pp collisions at s NN = 2.76 TeV at the LHC, are reported. The results are presented in several event centrality intervals and several kinematic regions, for transverse momenta p T > 6.5 GeV / c and rapidity | y | < 2.4 , extending down to p T = 3 GeV / c in the 1.6 < | y | < 2.4 range. The v 2 of prompt J / ψ is found to be nonzero, but with no strong dependence on centrality, rapidity, or p T over the full kinematic range studied. The measured v 2 of nonprompt J / ψ is consistent with zero. The R AA of prompt J / ψ exhibits a suppression that increases from peripheral to central collisions but does not vary strongly as a function of either y or p T in the fiducial range. The nonprompt J / ψ R AA shows a suppression which becomes stronger as rapidity or p T increases. The v 2 and R AA of open and hidden charm, and of open charm and beauty, are compared.

Normalized double-differential cross sections for top quark pair ( t t ¯ ) production are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS experiment at the LHC. The analyzed data correspond to an integrated luminosity of 19.7 fb - 1 . The measurement is performed in the dilepton e ± μ ∓ final state. The t t ¯ cross section is determined as a function of various pairs of observables characterizing the kinematics of the top quark and t t ¯ 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 t t ¯ cross sections in a fit of parametrized parton distribution functions is shown to have significant impact on the gluon distribution.

A bstract A measurement of the groomed jet mass in PbPb and pp collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector at the LHC is presented. Jet grooming is a recursive procedure which sequentially removes soft constituents of a jet until a pair of hard subjets is found. The resulting groomed jets can be used to study modifications to the parton shower evolution in the presence of the hot and dense medium created in heavy ion collisions. Predictions of groomed jet properties from the pythia and herwig ++ event generators agree with the measurements in pp collisions. When comparing the results from the most central PbPb collisions to pp data, a hint of an increase of jets with large jet mass is observed, which could originate from additional medium-induced radiation at a large angle from the jet axis. However, no modification of the groomed mass of the core of the jet is observed for all PbPb centrality classes. The PbPb results are also compared to predictions from the jewel and q - pythia event generators, which predict a large modification of the groomed mass not observed in the data.

A data sample of events from proton–proton collisions with two isolated same-sign leptons, missing transverse momentum, and jets is studied in a search for signatures of new physics phenomena by the CMS Collaboration at the LHC. The data correspond to an integrated luminosity of 35.9 fb - 1 , and a center-of-mass energy of 13 TeV . The properties of the events are consistent with expectations from standard model processes, and no excess yield is observed. Exclusion limits at 95% confidence level are set on cross sections for the pair production of gluinos, squarks, and same-sign top quarks, as well as top-quark associated production of a heavy scalar or pseudoscalar boson decaying to top quarks, and on the standard model production of events with four top quarks. The observed lower mass limits are as high as 1500 GeV for gluinos, 830 GeV for bottom squarks. The excluded mass range for heavy (pseudo)scalar bosons is 350–360 (350–410) GeV . Additionally, model-independent limits in several topological regions are provided, allowing for further interpretations of the results.

A search is presented for additional neutral Higgs bosons in the $\\tau\\tau$ final state in proton-proton collisions at the LHC. The search is performed in the context of the minimal supersymmetric extension of the standard model (MSSM), using the data collected with the CMS detector in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. To enhance the sensitivity to neutral MSSM Higgs bosons, the search includes production of the Higgs boson in association with b quarks. No significant deviation above the expected background is observed. Model-independent limits at 95% confidence level (CL) are set on the product of the branching fraction for the decay into $\\tau$ leptons and the cross section for the production via gluon fusion or in association with b quarks. These limits range from 18 pb at 90 GeV to 3.5 fb at 3.2 TeV for gluon fusion and from 15 pb (at 90 GeV) to 2.5 fb (at 3.2 TeV) for production in association with b quarks. In the m$_{\\text{h}}^{\\text{mod+}}$ scenario these limits translate into a 95% CL exclusion of $\\tan\\beta>$ 6 for neutral Higgs boson masses below 250 GeV, where $\\tan\\beta$ is the ratio of the vacuum expectation values of the neutral components of the two Higgs doublets. As a result the 95% CL exclusion contour reaches 1.6 TeV for $\\tan\\beta=$ 60.

A bstract A search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H → aa → b b ¯ b b ¯ . The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb − 1 . To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 < m a < 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp → WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction B H → aa → b b ¯ b b ¯ . The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for m a = 20 GeV to 0.36 for m a = 60 GeV, complementing other measurements in the μμττ , ττττ and bb ℓℓ ( ℓ = μ , τ ) channels.