Abstract
Abstract The $ \mathrm{t}\overline{\mathrm{t}} $ production cross section $ \left( {{\sigma_{{\mathrm{t}\overline{\mathrm{t}}}}}} \right) $ is measured in proton-proton collisions at $ \sqrt{s}=7 $ TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 fb−1. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of $ {\sigma_{{\mathrm{t}\overline{\mathrm{t}}}}} $ for a top-quark mass of 172.5 GeV is $ 161.9\pm 2.5\left( {\mathrm{stat}.} \right)_{-5.0}^{+5.1}\left( {\mathrm{syst}.} \right)\pm 3.6\,\left( {\mathrm{lumi}.} \right)\,\mathrm{pb} $ , consistent with the prediction of the standard model.
Highlights
Background estimatesThe main backgrounds in this analysis arise from DY, diboson, and single-top-quark events, where at least two prompt leptons are produced from Z or W decays
Starting from the nearly 100% decay of both top quarks through the electroweak transition t → Wb, we focus on events in the dilepton final states e+e−, μ+μ−, and e±μ∓, where both W bosons decay leptonically (W → ν ), but with contributions from W → τ ντ arising only when the τ leptons decay into ν ντ ( = e or μ) states
The particle energies within this cone, obtained using the particle-flow (PF) reconstruction algorithm [38], which provides a list of particles and their kinematic properties, are projected onto the plane transverse to the beam, and summed as scalar quantities, excluding the contribution from the lepton candidate
Summary
The central feature of the CMS apparatus is a superconducting solenoid, 13 m in length and 6 m in diameter, which provides an axial magnetic field of 3.8 T. The bore of the solenoid is outfitted with a variety of particle-detection systems. A crystal electromagnetic calorimeter (ECAL) and a brass/scintillator hadronic calorimeter surround the inner tracking volume and provide high-resolution measurements of energy (E) used to reconstruct electrons, photons and particle jets. Muons are measured in gas detectors embedded in the flux-return yoke of the solenoid. The detector is nearly hermetic, thereby providing reliable measurements of momentum imbalance in the plane transverse to the beams. A more detailed description of the CMS detector is given in ref. A more detailed description of the CMS detector is given in ref. [14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
