© 2016, CERN for the benefit of the CMS collaboration. A measurement of the decorrelation of azimuthal angles between the two jets with the largest transverse momenta is presented for seven regions of leading jet transverse momentum up to 2.2TeV. The analysis is based on the proton-proton collision data collected with the CMS experiment at a centre-of-mass energy of 8TeV corresponding to an integrated luminosity of 19.7fb-1. The dijet azimuthal decorrelation is caused by the radiation of additional jets and probes the dynamics of multijet production. The results are compared to fixed-order predictions of perturbative quantum chromodynamics (QCD), and to simulations using Monte Carlo event generators that include parton showers, hadronization, and multiparton interactions. Event generators with only two outgoing high transverse momentum partons fail to describe the measurement, even when supplemented with next-to-leading-order QCD corrections and parton showers. Much better agreement is achieved when at least three outgoing partons are complemented through either next-to-leading-order predictions or parton showers. This observation emphasizes the need to improve predictions for multijet production.

© 2016, CERN for the benefit of the CMS collaboration. The differential cross section and charge asymmetry for inclusive pp → 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 18.8fb-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.

© 2016, CERN for the benefit of the CMS collaboration. The double-differential inclusive jet cross section is measured as a function of jet transverse momentum pT and absolute rapidity |y|, using proton-proton collision data collected with the CMS experiment at the LHC, at a center-of-mass energy of √s = 2.76 TeV and corresponding to an integrated luminosity of 5.43 pb-1. Jets are reconstructed within the pT range of 74 to 592 GeV and the rapidity range |y|<3.0. The reconstructed jet spectrum is corrected for detector resolution. The measurements are compared to the theoretical prediction at next-to-leading-order QCD using different sets of parton distribution functions. This inclusive cross section measurement explores a new kinematic region and is consistent with QCD predictions.

© 2016, CERN for the benefit of the CMS collaboration. A measurement of the W boson pair production cross section in proton-proton collisions at √s = 8 TeV is presented. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 19.4fb-1. The W +W - candidates are selected from events with two charged leptons, electrons or muons, and large missing transverse energy. The measured W +W - cross section is 60.1 ± 0.9 (stat) ± 3.2 (exp) ± 3.1 (theo) ± 1.6 (lumi) pb = 60.1±4.8 pb, consistent with the standard model prediction. The W +W - cross sections are also measured in two different fiducial phase space regions. The normalized differential cross section is measured as a function of kinematic variables of the final-state charged leptons and compared with several perturbative QCD predictions. Limits on anomalous gauge couplings associated with dimension-six operators are also given in the framework of an effective field theory. The corresponding 95 % confidence level intervals are -5.7

© 2016, CERN for the benefit of the CMS collaboration. A measurement of the double-differential inclusive jet cross section as a function of jet transverse momentum pTand absolute jet rapidity | y| is presented. The analysis is based on proton–proton collisions collected by the CMS experiment at the LHC at a centre-of-mass energy of 13TeV. The data samples correspond to integrated luminosities of 71 and 44pb-1 for | y| < 3 and 3.2 < | y| < 4.7 , respectively. Jets are reconstructed with the anti-ktclustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase space region covering jet pTup to 2TeV and jet rapidity up to | y| = 4.7. Predictions of perturbative quantum chromodynamics at next-to-leading order precision, complemented with electroweak and nonperturbative corrections, are used to compute the absolute scale and the shape of the inclusive jet cross section. The cross section difference in R, when going to a smaller jet size of 0.4, is best described by Monte Carlo event generators with next-to-leading order predictions matched to parton showering, hadronisation, and multiparton interactions. In the phase space accessible with the new data, this measurement provides a first indication that jet physics is as well understood at s=13TeV as at smaller centre-of-mass energies.

© 2016, CERN for the benefit of the CMS collaboration. Jet multiplicity distributions in top quark pair (t t ¯) events are measured in pp collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC using a data set corresponding to an integrated luminosity of 19.7fb-1. The measurement is performed in the dilepton decay channels (e+e-, μ+μ-, and e±μ∓). The absolute and normalized differential cross sections for t t ¯ production are measured as a function of the jet multiplicity in the event for different jet transverse momentum thresholds and the kinematic properties of the leading additional jets. The differential t t ¯ b and t t ¯ b b ¯ cross sections are presented for the first time as a function of the kinematic properties of the leading additional b jets. Furthermore, the fraction of events without additional jets above a threshold is measured as a function of the transverse momenta of the leading additional jets and the scalar sum of the transverse momenta of all additional jets. The data are compared and found to be consistent with predictions from several perturbative quantum chromodynamics event generators and a next-to-leading order calculation.

© 2016, CERN for the benefit of the CMS collaboration. Results are reported from a search for the pair production of top squarks, the supersymmetric partners of top quarks, in final states with jets and missing transverse momentum. The data sample used in this search was collected by the CMS detector and corresponds to an integrated luminosity of 18.9fb-1 of proton-proton collisions at a centre-of-mass energy of 8TeV produced by the LHC. The search features novel background suppression and prediction methods, including a dedicated top quark pair reconstruction algorithm. The data are found to be in agreement with the predicted backgrounds. Exclusion limits are set in simplified supersymmetry models with the top squark decaying to jets and an undetected neutralino, either through a top quark or through a bottom quark and chargino. Models with the top squark decaying via a top quark are excluded for top squark masses up to 755GeV in the case of neutralino masses below 200GeV. For decays via a chargino, top squark masses up to 620GeV are excluded, depending on the masses of the chargino and neutralino.

© 2016, CERN for the benefit of the CMS collaboration. Inclusive jet production in pPb collisions at a nucleon–nucleon (NN) center-of-mass energy of √sNN= 5.02TeV is studied with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 30.1 nb- 1is analyzed. The jet transverse momentum spectra are studied in seven pseudorapidity intervals covering the range - 2.0 < ηCM< 1.5 in the NN center-of-mass frame. The jet production yields at forward and backward pseudorapidity are compared and no significant asymmetry about ηCM= 0 is observed in the measured kinematic range. The measurements in the pPb system are compared to reference jet spectra obtained by extrapolation from previous measurements in pp collisions at √s=7TeV. In all pseudorapidity ranges, nuclear modifications in inclusive jet production are found to be small, as predicted by next-to-leading order perturbative QCD calculations that incorporate nuclear effects in the parton distribution functions.

© 2017, CERN for the benefit of the CMS collaboration. The first measurement of the jet mass mjetof top quark jets produced in t t ¯ events from pp collisions at s=8TeV is reported for the jet with the largest transverse momentum pTin highly boosted hadronic top quark decays. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7fb-1. The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay t → b W with W → ℓν where ℓ is an electron or muon, are used to select t t ¯ events with large Lorentz boosts. The products of the fully hadronic decay t → b W with W → q q ¯′are reconstructed using a single Cambridge–Aachen jet with distance parameter R= 1.2 , and pT> 400 GeV. The t t ¯ cross section as a function of mjetis unfolded at the particle level and is used to test the modelling of highly boosted top quark production. The peak position of the mjetdistribution is sensitive to the top quark mass mt, and the data are used to extract a value of mtto assess this sensitivity.

© 2016, CERN for the benefit of the CMS collaboration. A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at s=8TeV. The data correspond to an integrated luminosity of 19.7fb-1. The search considers H H resonances with masses between 1 and 3TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t t ¯ events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 % confidence level for the product of the production cross section and branching fraction σ(gg→X)B(X→HH→bb¯bb¯) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0TeV, significantly extending previous searches. For a warped extra dimension theory with a mass scale ΛR= 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55TeV.