1,740 research outputs found

    Latest CMS Heavy-Ion Results on Jets

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    Jet studies provide an experimental method to explore the features of energy loss in the strongly interacting quark-gluon plasma. Recent jet results from 2.76 TeV PbPb and pp collisions measured with the CMS detector are presented. Jets in the most head-on (central) PbPb collisions are quenched in comparison to pp, and the jets fragment in different ways in the two systems. Measurements from pPb collisions at 5.02 TeV show that the jet and charged particle suppression seen in central PbPb measurements are not due to initial state nuclear effects.Comment: 6 pages, 4 figure

    Inclusive jet and charged hadron nuclear modification factors in PbPb collisions at 2.76 TeV with CMS

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    AbstractMeasurements are reported for charged hadron and inclusive jet transverse momentum (pT) spectra in pp and PbPb collisions at a nucleon‚Äďnucleon center-of-mass energy of 2.76 TeV with the CMS detector. These measurements make use of the high-statistics jet-triggered data recorded in 2011, including the total available PbPb luminosity of 150őľb‚ąí1. Charged particles are reconstructed using an iterative algorithm and spurious high-pT tracks are suppressed by requiring appropriate energy deposits in the calorimeter system. Jets are reconstructed with the anti-kT algorithm, using combined information from tracking and calorimetry. The charged particle pT distributions are measured in the pseudorapidity range of |ő∑|<1, and pT up to 100 GeV/c. The jet pT distributions are measured in the pseudorapidity range of |ő∑|<2, and pT from 100 to 300 GeV/c. The nuclear modification factors, RAA, for charged hadrons and jets are presented as a function of pT and collision centrality. In the range pT=5‚Äď10 GeV/c the charged hadron production in PbPb collisions is suppressed by up to a factor of seven, compared to the pp yield scaled by the number of incoherent nucleon‚Äďnucleon collisions. The charged hadron RAA increases at higher pT and approaches a value of approximately 0.5 in the range pT=40‚Äď100 GeV/c for the most central collisions

    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