A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tt events under typical 2011 pileup conditions, the average trackreconstruction efficiency for promptly-produced charged particles with transverse momenta of p T > 0.9 GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p T = 100 GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p T , and respectively, 10 µm and 30 µm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 µm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.

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Several techniques have been employed to incise the temporalis muscle for the pterional craniotomy. The authors describe a method which provides the advantage of a free bone flap, yet allows anatomical reapproximation of the temporalis muscle to its bone attachment.

A search is performed for the production of heavy resonances decaying into topantitop quark pairs in proton-proton collisions at √ s = 8 TeV. Data used for the analyses were collected with the CMS detector and correspond to an integrated luminosity of 19.7 fb −1 . The search is performed using events with three different final states, defined by the number of leptons (electrons and muons) from the tt → WbWb decay. The analyses are optimized for reconstruction of top quarks with high Lorentz boosts, where jet substructure techniques are used to enhance the sensitivity. Results are presented for all channels and a combination is performed. No significant excess of events relative to the expected yield from standard model processes is observed. Upper limits on the production cross section of heavy resonances decaying to tt are calculated. A narrow leptophobic topcolor Z resonance with a mass below 2.4 TeV is excluded at 95% confidence level. Limits are also derived for a broad Z resonance with a 10% width relative to the resonance mass, and a Kaluza-Klein excitation of the gluon in the Randall-Sundrum model. These are the most stringent limits to date on heavy resonances decaying into top-antitop quark pairs. Published in Physical Review D asThe CMS experiment uses a particle-flow (PF) based event reconstruction [37,38], which aggregates input from all subdetectors. This information includes charged-particle tracks from the tracking system and deposited energy from the electromagnetic and hadronic calorimeters, taking advantage of excellent granularity of the sub-systems. Particles are classified as electrons, muons, photons, charged hadrons, and neutral hadrons. Primary vertices are reconstructed using a deterministic annealing filter algorithm [39]. The vertex with the largest squared sum of the associated track p T values is taken to be the primary event vertex.Electrons are reconstructed in the pseudorapidity range |η| < 2.5, by combining tracking information with energy deposits in the electromagnetic calorimeter [40,41]. Electron candidates are required to originate from the primary event vertex. Electrons are identified using infor-6 5 Reconstruction of tt events B The CMS Collaboration

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