A search is presented in protonaproton collisions at s = 7 TeV for fermionic triplet states expected in type III seesaw models. The search is performed using final states with three isolated charged ...leptons and an imbalance in transverse momentum. The data, collected with the CMS detector at the LHC, correspond to an integrated luminosity of 4.9 fb - 1 . No excess of events is observed above the background predicted by the standard model, and the results are interpreted in terms of limits on production cross sections and masses of the heavy partners of the neutrinos in type III seesaw models. Depending on the considered scenarios, lower limits are obtained on the mass of the heavy partner of the neutrino that range from 180 to 210 GeV . These are the first limits on the production of type III seesaw fermionic triplet states reported by an experiment at the LHC.
The results of a search for the pair production of a fourth-generation up-type quark (t a2) in protonaproton collisions at s = 7 TeV are presented, using data corresponding to an integrated ...luminosity of about 5.0 fb-1 collected by the Compact Muon Solenoid experiment at the LHC. The t a2 quark is assumed to decay exclusively to a W boson and a b quark. Events with a single isolated electron or muon, missing transverse momentum, and at least four hadronic jets, of which at least one must be identified as a b jet, are selected. No significant excess of events over standard model expectations is observed. Upper limits for the t a2 t A= a2 production cross section at 95% confidence level are set as a function of t a2 mass, and t a2 -quark production for masses below 570 GeV is excluded. The search is equally sensitive to nonchiral heavy quarks decaying to Wb. In this case, the results can be interpreted as upper limits on the production cross section times the branching fraction to Wb.
The inclusive cross section for top-quark pair production measured by the CMS experiment in proton-proton collisions at a center-of-mass energy of 7 TeV is compared to the QCD prediction at ...next-to-next-to-leading order with various parton distribution functions to determine the top-quark pole mass, mtpole, or the strong coupling constant, alphaS. With the parton distribution function set NNPDF2.3, a pole mass of 176.7+3.8-3.4 GeV is obtained when constraining alphaS at the scale of the Z boson mass, mZ, to the current world average. Alternatively, by constraining mtpole to the latest average from direct mass measurements, a value of alphaS(mZ) = 0.1151+0.0033-0.0032 is extracted. This is the first determination of alphaS using events from top-quark production.
The inclusive jet cross section is measured in pp collisions with a center-of-mass energy of 7 TeV at the Large Hadron Collider using the CMS experiment. The data sample corresponds to an integrated ...luminosity of 34 pb{sup -1}. The measurement is made for jet transverse momenta in the range 18-1100 GeV and for absolute values of rapidity less than 3. The measured cross section extends to the highest values of jet p{sub T} ever observed and, within the experimental and theoretical uncertainties, is generally in agreement with next-to-leading-order perturbative QCD predictions.
A search is presented for charge-asymmetric production of a W ' boson that has been proposed to accommodate the forward-backward asymmetry observed in the production of top-antitop quark pairs at the ...Tevatron. The new heavy W ' boson would be produced in association with a top quark and would decay into top and down quarks. The data correspond to an integrated luminosity of 5.0 fb-1 in pp collisions at a center-of-mass energy of 7 TeV, recorded by the CMS detector at the LHC. No significant excess above the standard model expectations is observed, and, from a combination of the electron-plus-jets and muon-plus-jets channels, a 95% confidence level lower limit of 840 GeV / c 2 is set on the W ' boson mass for a W ' boson model with values for coupling constants to top and down quarks g L = 0 and g R = 2 . In addition, a kinematic reconstruction of the W ' resonance mass using the inherent charge asymmetry of this model finds no indication of the presence of W ' events in the data.
A search for three-jet hadronic resonance production in pp collisions at a center-of-mass energy of 7 TeV has been conducted by the CMS Collaboration at the LHC, using a data sample corresponding to ...an integrated luminosity of 35 pb{sup -1}. Events with high jet multiplicity and a large scalar sum of jet transverse momenta are analyzed using a signature-based approach. The number of expected standard model background events is found to be in good agreement with the observed events. Limits on the cross section times branching ratio are set in a model of gluino pair production with an R-parity-violating decay to three quarks, and the data rule out such particles within the mass range of 200 to 280 GeV/c{sup 2}.
Electroweak production of the top quark is measured for the first time in pp collisions at {radical}(s)=7 TeV, using a data set collected with the CMS detector at the LHC and corresponding to an ...integrated luminosity of 36 pb{sup -1}. With an event selection optimized for t-channel production, two complementary analyses are performed. The first one exploits the special angular properties of the signal, together with background estimates from the data. The second approach uses a multivariate analysis technique to probe the compatibility with signal topology expected from electroweak top-quark production. The combined measurement of the cross section is 83.6{+-}29.8(stat+syst){+-}3.3(lumi) pb, consistent with the standard model expectation.
A search for the standard model Higgs boson decaying to W+W- in pp collisions at sqrt(s) = 7 TeV is reported. The data are collected at the LHC with the CMS detector, and correspond to an integrated ...luminosity of 4.6 inverse femtobarns. The W+W- candidates are selected in events with two charged leptons and large missing transverse energy. No significant excess of events above the standard model background expectations is observed, and upper limits on the Higgs boson production relative to the standard model Higgs expectation are derived. The standard model Higgs boson is excluded in the mass range 129-270 GeV at 95% confidence level.
A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (E T miss). This signature is motivated by BSM physics scenarios, ...including supersymmetry. The study is performed using a sample of proton-proton collision data collected at s = 7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 fb-1. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling E T miss with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.
A search for high-mass resonances decaying into t + t - is performed using a data sample of pp collisions at s = 7 TeV . The data were collected with the CMS detector at the LHC and correspond to an ...integrated luminosity of 4.9 fb-1. The number of observed events is in agreement with the standard model prediction. An upper limit on the product of the resonance cross section and branching fraction into t-lepton pairs is calculated as a function of the resonance mass. Using the sequential standard model resonance Z SSM ' and the superstring-inspired E 6 model with resonance Z ? ' as benchmarks, resonances with standard model couplings with masses below 1.4 and 1.1 TeV, respectively, are excluded at 95% confidence level.
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