1,742 research outputs found

    Optimization of Jet Reconstruction Settings and Parton-Level Correction for the ttH Channel

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    The typical final state for a tbar H associated production where the Higgs decays into a pair of b quark is a high multi-jet event. The expected jet number for one (two) semi-leptonic top decay or fully hadronic top decay is respectively 6(4) and 8. All the proposed techniques to optimize signal selection with respect to background suppression use mainly lepton tag, jet energy cut and b-tagging. The choice of the jet algorithm is therefore crucial to improve the chance to detect a light Higgs boson in the top-associated H production. Many previous studies both with fast and full simulated events show that different jet algorithms give different results in the selection procedure. To fully investigate the effect of different jet algorithm is however mandatory to use calibrated jet both from detector effects and jet formation physical model point of view. The different jet finders and Monte-Carlo jet calibration parameters are studied relatively to the best performance for the tbar H channel observability. The set of algorithm chosen is iterative cone algorithm with cone size going from 0.30 up to 0.50 (with 0.05 step) and inclusive K perp~ algorithm with r=0.4.Different calibration parameters as a function of eta, E_T and jet flavor have been calculated. Finally an example of different jet to parton pairing efficiency for the fully hadronic ttbar H decay is computed

    Perspectives for Top Quark Physics at LHC

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    The Large Hadron Collider (LHC) will provide a huge amount of top-antitop events, making the LHC a top quark factory. Precision measurements in the top quark sector will allow for a detailed study of electroweak (and flavour) symmetry breaking mechanisms. All the properties of the top quark will be obtained, based on the measurement of its mass, cross section and decay branching fraction. The large top quark sample available from the start of LHC will also play an important role in commissioning the ATLAS and CMS detectors during the first data-taking period. A brief overview of the top quark measurements within the Standard Model is given, together with a reviw of possible new physics scenarios in production and decay mechanisms

    Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

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    During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented

    Differential cross section measurements for the production of a W boson in association with jets in proton‚Äďproton collisions at ‚ąös = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript ‚ąí1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an