A search for excited leptons is carried out with the CMS detector at the LHC, using 36 pb-1 of pp collision data recorded at inline image. The search is performed for associated production of a ...lepton and an oppositely charged excited lepton ppright arrowa""a"" super(a), followed by the decay a"" super(a) infinity ""gamma, resulting in the a""a""gamma final state, where a""=e, mu . No excess of events above the standard model expectation is observed. Interpreting the findings in the context of a"" super(a) production through four-fermion contact interactions and subsequent decay via electroweak processes, first upper limits are reported for a"" super(a) production at this collision energy. The exclusion region in the compositeness scale I> and excited lepton mass Ma"" super(a) parameter space is extended beyond previously established limits. For I>=Ma"" super(a), excited lepton masses are excluded below 1070 GeV/c super(2) for e super(a) and 1090 GeV/c super(2) for mu super(a) at the 95% confidence level.
A measurement of the double-differential inclusive dijet production cross section in proton-proton collisions at inline image is presented as a function of the dijet invariant mass and jet rapidity. ...The data correspond to an integrated luminosity of 36 pbsuper-1, recorded with the CMS detector at the LHC. The measurement covers the dijet mass range 0.2 TeV to 3.5 TeV and jet rapidities up to
Hadronic event shapes have been measured in proton-proton collisions at inline image, with a data sample collected with the CMS detector at the LHC. The sample corresponds to an integrated luminosity ...of 3.2 pbsuper-1. Event-shape distributions, corrected for detector response, are compared with five models of QCD multijet production.
A measurement of Wsuper+Wsuper- production in pp collisions at inline image and a search for the Higgs boson are reported. The Wsuper+Wsuper- candidates are selected in events with two leptons, ...either electrons or muons. The measurement is performed using LHC data recorded with the CMS detector, corresponding to an integrated luminosity of 36 pbsuper-1. The pp --> Wsuper+Wsuper- cross section is measured to be inline image, consistent with the standard model prediction. Limits on WWgamma and WWZ anomalous triple gauge couplings are set. The search for the standard model Higgs boson in the Wsuper+Wsuper- decay mode does not reveal any evidence of excess above backgrounds. Limits are set on the production of the Higgs boson in the context of the standard model and in the presence of a sequential fourth family of fermions with high masses. In the latter context, a Higgs boson with mass between 144 and 207 GeV/csuper2 is ruled out at 95% confidence level.
A search for a heavy gauge boson Wsuper' has been conducted by the CMS experiment at the LHC in the decay channel with an electron and large transverse energy imbalance inline image, using ...proton-proton collision data corresponding to an integrated luminosity of 36 pbsuper-1. No excess above standard model expectations is seen in the transverse mass distribution of the electron-inline image system. Assuming standard-model-like couplings and decay branching fractions, a Wsuper' boson with a mass less than 1.36 TeV/csuper2 is excluded at 95% confidence level.
Results are presented of a search for compositeness in electrons and muons using a data sample of pp collisions at a center-of-mass energy s = 7 TeV collected with the CMS detector at the LHC and ...corresponding to an integrated luminosity of 5.0 fb - 1 . Excited leptons (a a) are assumed to be produced via contact interactions in conjunction with a standard model lepton and to decay via a a a a gamma , yielding a final state with two energetic leptons and a photon. The number of events observed in data is consistent with that expected from the standard model. The 95% confidence upper limits for the cross section for the production and decay of excited electrons (muons), with masses ranging from 0.6 to 2 TeV, are 1.48 to 1.24 fb (1.31 to 1.11 fb). Excited leptons with masses below 1.9 TeV are excluded for the case where the contact interaction scale equals the excited lepton mass. The limits on the cross sections are the most stringent ones published to date.
A measurement of the t t A= production cross section in pp collisions at s = 7 TeV is presented. The results are based on data corresponding to an integrated luminosity of 2.3 fb-1 collected by the ...CMS detector at the LHC. Selected events are required to have one isolated, high transverse momentum electron or muon, large missing transverse energy, and hadronic jets, at least one of which must be consistent with having originated from a b quark. The measured cross section is 158.1 +/- 2.1 (stat .) +/- 10.2 (syst .) +/- 3.5 (lum .) pb , in agreement with standard model predictions.
Many models of new physics, including versions of supersymmetry (SUSY), predict production of events with low missing transverse energy, electroweak gauge bosons, and many energetic final-state ...particles. The stealth SUSY model yields this signature while conserving R-parity by means of a new hidden sector in which SUSY is approximately conserved. The results of a general search for new physics, with no requirement on missing transverse energy, in events with two photons and four or more hadronic jets are reported. The study is based on a sample of protonaproton collisions at s = 7 TeV corresponding to 4.96 fb - 1 of integrated luminosity collected with the CMS detector in 2011. Based on good agreement between the data and the standard model expectation, the data are used to determine model-independent cross-section limits and a limit on the squark mass in the framework of stealth SUSY. With this first study of its kind, squark masses less than 1430 GeV are excluded at the 95% confidence level.
An updated search for heavy narrow resonances decaying to muon or electron pairs using the CMS detector is presented. Data samples from pp collisions at s = 7 TeV and 8 TeV at the LHC, with ...integrated luminosities of up to 5.3 and 4.1 fb - 1 , respectively, are combined. No evidence for a heavy narrow resonance is observed. The analysis of the combined data sets excludes, at 95% confidence level, a Sequential Standard Model Z SSM a2 resonance lighter than 2590 GeV, a superstring-inspired Z I a2 lighter than 2260 GeV, and KaluzaaKlein gravitons lighter than 2390 (2030) GeV, assuming that the coupling parameter k / M A= Pl is 0.10 (0.05). These are the most stringent limits to date.
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