A. Lopez Virto

Study of Z Boson Production in PbPb Collisions at √sNN=2.76 TeV

A search for Z bosons in the μ+μ− decay channel has been performed in PbPb collisions at √ sNN = 2.76 TeV with the CMS detector at the LHC, in a 7.2 μb−1 data sample. The number of opposite-sign muon pairs observed in the 60–120 GeV/c2 invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of (33.8± 5.5(stat) ± 4.4(syst)) × 10−8, in the |y| < 2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions. Submitted to Physical Review Letters ∗See Appendix A for the list of collaboration members ar X iv :1 10 2. 54 35 v1 [ nu cl -e x] 2 6 Fe b 20 11A search for Z bosons in the μ(+)μ(-) decay channel has been performed in PbPb collisions at √S(NN)=2.76  TeV with the CMS detector at the LHC, in a 7.2 μb(-1) data sample. The number of opposite-sign muon pairs observed in the 60-120 GeV/c(2) invariant mass range is 39, corresponding to a yield per unit of rapidity (y) and per minimum bias event of [33.8±5.5(stat)±4.4(syst)]×10(-8), in the |y|<2.0 range. Rapidity, transverse momentum, and centrality dependencies are also measured. The results agree with next-to-leading order QCD calculations, scaled by the number of incoherent nucleon-nucleon collisions.

Search for exotic particles decaying to WZ in pp collisions at √s=7 TeV

A bstractA search for new exotic particles decaying to the VZ final state is performed, where V is either a W or a Z boson decaying into two overlapping jets and the Z decays into a pair of electrons, muons or neutrinos. The analysis uses a data sample of pp collisions corresponding to an integrated luminosity of 5 fb−1 collected by the CMS experiment at the LHC at

Erratum: Search for anomalous tt¯ production in the highly-boosted all-hadronic final state

\sqrt{s}=7

Erratum: Measurement of the tt¯ production cross section in the dilepton channel in pp collisions at √s = 8 TeV

TeV in 2011. No significant excess is observed in the mass distribution of the VZ candidates compared with the background expectation from standard model processes. Model-dependent upper limits at the 95% confidence level are set on the product of the cross section times the branching fraction of hypothetical particles decaying to the VZ final state as a function of mass. Sequential standard model W′ bosons with masses between 700 and 940 GeV are excluded. In the Randall-Sundrum model for graviton resonances with a coupling parameter of 0.05, masses between 750 and 880 GeV are also excluded.

Measurements of inclusive W and Z cross sections in pp collisions at ps = 7 TeV

A search is presented for a massive particle, generically referred to as a Z′, decaying into a tt− pair. The search focuses on Z′ resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 fb−1. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z′ modeled for several widths, as well as for a Randall-Sundrum Kaluza-Klein gluon. In addition, the result contrain any enhancement in tt− production beyond expectations of the standard mode for tt invariant mass larger than 1 TeV/c2.

Measurement of the inclusive W and Z production cross sections in pp collisions at ps = 7TeV with the CMS experiment

In this study, the top-antitop quark (tt¯) production cross section is measured in proton-proton collisions at √s = 8 TeV with the CMS experiment at the LHC, using a data sample corresponding to an integrated luminosity of 5.3 fb–1. The measurement is performed by analysing events with a pair of electrons or muons, or one electron and one muon, and at least two jets, one of which is identified as originating from hadronisation of a bottom quark. The measured cross section is 239±2 (stat.)±11 (syst.)±6 (lum.) pb, for an assumed top-quark mass of 172.5 GeV, in agreement with the prediction of the standard model.

Strange particle production in pp collisions at ps = 0.9 and 7 TeV

Measurements of inclusive W and Z boson production cross sections in pp collisions at sqrt(s)=7 TeV are presented, based on 2.9 inverse picobarns of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give sigma(pp to WX) times B(W to muon or electron + neutrino) = 9.95 \pm 0.07(stat.) \pm 0.28(syst.) \pm 1.09(lumi.) nb and sigma(pp to ZX) times B(Z to oppositely charged muon or electron pairs) = 0.931 \pm 0.026(stat.) \pm 0.023(syst.) \pm 0.102(lumi.) nb. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reported.Measurements of inclusive W and Z boson production cross sections in pp collisions at

Searches for new physics using the tt̄ invariant mass distribution in pp collisions at √s=8 TeV

\sqrt {s} = 7

Simulation of electrical parameters of new design of SLHC silicon sensors for large radii

TeV are presented, based on 2.9 pb−1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give