Search for charge-asymmetric production of W\u27 bosons in tt + jet events from pp collisions at √s = 7 TeV

A search is presented for charge-asymmetric production of a W\u27 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\u27 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-plusjets and muon-plus-jets channels, a 95% confidence level lower limit of 840 GeV/c2 is set on the W\u27 boson mass for a W\u27 boson model with values for coupling constants to top and down quarks gL = 0 and gR = 2. In addition, a kinematic reconstruction of the W[1] resonance mass using the inherent charge asymmetry of this model finds no indication of the presence of W\u27 events in the data

Search for New Physics with a Monojet and Missing Transverse Energy in pp Collisions at √s= 7 TeV

A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a center-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb-1. An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved

Search for New Physics with a Monojet and Missing Transverse Energy in pp Collisions at √s= 7 TeV

A study of events with missing transverse energy and an energetic jet is performed using pp collision data at a center-of-mass energy of 7 TeV. The data were collected by the CMS detector at the LHC, and correspond to an integrated luminosity of 36 pb-1. An excess of these events over standard model contributions is a signature of new physics such as large extra dimensions and unparticles. The number of observed events is in good agreement with the prediction of the standard model, and significant extension of the current limits on parameters of new physics benchmark models is achieved

Search for the Standard Model Higgs Boson in the Decay Channel H → ZZ → 4l in pp Collisions at √s = 7 TeV

A search for a Higgs boson in the four-lepton decay channel H→ZZ, with each Z boson decaying to an electron or muon pair, is reported. The search covers Higgs boson mass hypotheses in the range of 110 \u3c mH \u3c 600 GeV. The analysis uses data corresponding to an integrated luminosity of 4.7 fb-1 recorded by the CMS detector in pp collisions at √s = 7 TeV from the LHC. Seventy- two events are observed with four-lepton invariant mass m4ℓ \u3e 100 GeV (with 13 below 160 GeV), while 67.1 ± 6.0 (9.5 ± 1.3) events are expected from background. The four-lepton mass distribution is consistent with the expectation of standard model background production of ZZ pairs. Upper limits at 95% confidence level exclude the standard model Higgs boson in the ranges of 134–158 GeV, 180–305 GeV, and 340–465 GeV. Small excesses of events are observed around masses of 119, 126, and 320 GeV, making the observed limits weaker than expected in the absence of a signal

Search for neutral Higgs bosons decaying to tau pairs in pp collisions at √s = 7 TeV

A search for neutral Higgs bosons decaying to tau pairs at a center-of-mass energy of 7 TeV is performed using a dataset corresponding to an integrated luminosity of 4.6 fb−1 recorded by the CMS experiment at the LHC. The search is sensitive to both the standard model Higgs boson and to the neutral Higgs bosons predicted by the minimal super symmetric extension of the standard model (MSSM). No excess of events is observed in the tau-pair invariant-mass spectrum. For a standard model Higgs boson in the mass range of 110–145 GeV upper limits at 95% confidence level (CL) on the production cross section are determined. We exclude a Higgs boson with mH = 115 GeV with a production cross section 3.2 times of that predicted by the standard model. In the MSSM, upper limits on the neutral Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, mA, sets stringent new bounds in the parameter space, excluding at 95% CL values of tan β as low as 7.1 at mA = 160 GeV in the mmaxh benchmark scenario

Search for heavy, top-like quark pair production in the dilepton final state in pp collisions at √s = 7 TeV

The results of a search for pair production of a heavy, top-like quark, t\u27, in the decay mode t\u27t̅\u27 → bW+ b̅W− → bℓ +νb̅ℓ −ν̅ are presented. The search is performed with a data sample corresponding to an integrated luminosity of 5.0 fb−1 in pp collisions at a center-of-mass energy of 7 TeV, collected by the CMS experiment at the LHC. The observed number of events agrees with the expectation from standard model processes, and no evidence of t\u27t̅\u27 production is found. Upper limits on the production cross section as a function of t\u27 mass are presented, and t\u27 masses below 557 GeV/c2 are excluded at the 95% confidence level

Measurement of the t-Channel Single Top Quark Production Cross Section in pp̅ Collisions at √s= 7 TeV

Electroweak production of the top quark is measured for the first time in pp collisions at √s= 7 TeV, using a data set collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 pb-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

Search for Signatures of Extra Dimensions in the Diphoton Mass Spectrum at the Large Hadron Collider

A search for signatures of extra spatial dimensions in the diphoton invariant-mass spectrum has been performed with the CMS detector at the LHC. No excess of events above the standard model expectation is observed using a data sample collected in proton-proton collisions at √s = 7 TeV corresponding to an integrated luminosity of 2.2 fb-1. In the context of the large-extra-dimensions model, lower limits are set on the effective Planck scale in the range of 2.3–3.8 TeV at the 95% confidence level. These limits are the most restrictive bounds on virtual-graviton exchange to date. The most restrictive lower limits to date are also set on the mass of the first graviton excitation in the Randall-Sundrum model in the range of 0.86–1.84 TeV, for values of the associated coupling parameter between 0.01 and 0.10

Measurement of the B0s Production Cross Section with B0s → J/ Decays in pp Collisions at √s = 7 TeV

The B0s differential production cross section is measured as functions of the transverse momentum and rapidity in pp collisions at √s= 7 TeV, using the B0s → J/UO decay, and compared with predictions based on perturbative QCD calculations at next-to-leading order. The data sample, collected by the CMS experiment at the LHC, corresponds to an integrated luminosity of 40 pb-1. The B0s is reconstructed from the decays J/U → µ+µ- and O→ K+K- The integrated B0s cross section times B0s→ J/UO branching fraction in the range 8BT\u3c 50 GeV/c and │yB \u3c 2.4 is measured to be 6.9 ± 0.6 ± 0.6 nb, where the first uncertainty is statistical and the second is systematic