CMS tracking performance results from early LHC operation
European Physical Journal C 70:4 (2010) 1165-1192
Abstract:
The first LHC pp collisions at centre-of-mass energies of 0.9 and 2.36 TeV were recorded by the CMS detector in December 2009. The trajectories of charged particles produced in the collisions were reconstructed using the all-silicon Tracker and their momenta were measured in the 3.8 T axial magnetic field. Results from the Tracker commissioning are presented including studies of timing, efficiency, signal-to-noise, resolution, and ionization energy. Reconstructed tracks are used to benchmark the performance in terms of track and vertex resolutions, reconstruction of decays, estimation of ionization energy loss, as well as identification of photon conversions, nuclear interactions, and heavy-flavour decays. © 2010 CERN for the benefit of the CMS collaboration.Measurement of the WW+WZ production cross section using a matrix element technique in lepton+jets events
Physical Review D - Particles, Fields, Gravitation and Cosmology 82:11 (2010)
Abstract:
We present a measurement of the WW+WZ production cross section observed in a final state consisting of an identified electron or muon, two jets, and missing transverse energy. The measurement is carried out in a data sample corresponding to up to 4.6fb⊃-1 of integrated luminosity at √s=1.96TeV collected by the CDF II detector. Matrix element calculations are used to separate the diboson signal from the large backgrounds. The WW+WZ cross section is measured to be 17.4±3.3pb in agreement with standard model predictions. A fit to the dijet invariant mass spectrum yields a compatible cross section measurement. © 2010 The American Physical Society.Search for dijet resonances in 7 TeV pp collisions at CMS
Physical Review Letters 105:21 (2010)
Abstract:
A search for narrow resonances in the dijet mass spectrum is performed using data corresponding to an integrated luminosity of 2.9pb⊃-1 collected by the CMS experiment at the Large Hadron Collider. Upper limits at the 95% confidence level are presented on the product of the resonance cross section, branching fraction into dijets, and acceptance, separately for decays into quark-quark, quark-gluon, or gluon-gluon pairs. The data exclude new particles predicted in the following models at the 95% confidence level: string resonances, with mass less than 2.50 TeV, excited quarks, with mass less than 1.58 TeV, and axigluons, colorons, and E6 diquarks, in specific mass intervals. This extends previously published limits on these models. Copyright © 2010 American Physical Society.Updated search for the flavor-changing neutral-current decay D0→μ⊃+μ⊃- in pp̄ collisions at √s=1.96 TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 82:9 (2010)
Abstract:
We report on a search for the flavor-changing neutral-current decay D0→μ⊃+μ⊃- in pp̄ collisions at √s=1.96TeV using 360pb⊃-1 of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D0 candidates in the μ⊃+μ⊃-, π⊃+π⊃-, and K⊃-π⊃+ decay modes. We use the Cabibbo-favored D0→K⊃- π⊃+ channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D0→π⊃+π⊃- channel for normalization. We set an upper limit on the branching fraction B(D0→μ⊃+μ⊃-)<2.1×10⊃-7(3.0×10⊃-7) at the 90% (95%) confidence level. © 2010 The American Physical Society.Search for R-parity violating decays of sneutrinos to eμ, μτ, and eτ pairs in pp collisions at square root s = 1.96 TeV.
Phys Rev Lett 105:19 (2010) 191801