2,914 research outputs found

    Measurement of charged jet cross sections and jet shapes in proton-proton collisions at sqrt(s) = 2.76 TeV with the ALICE detector at LHC

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    We present measurements of charged jet cross sections and jet shape observables in leading jet in proton-proton (pp) collisions at sqrt(s) = 2.76 TeV with the ALICE detector at LHC. Jets are reconstructed at the midrapidity from charged particle using sequential recombination anti-kT jet finding algorithm for various R values. The results are compared to measurements from HERWIG, PHOJET and different tunes of PYTHIA6 and earlier measurements at 7 TeV.Comment: Proceedings of XXII DAE-BRNS High Energy Physics Symposium 2016 conference, 12-16 December, 201

    Charm-quark fragmentation with an effective coupling constant

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    We use a recently proposed non-perturbative model, based on an effective strong coupling constant and free from tunable parameters, to study c-flavoured hadron production in e+e- annihilation. Charm-quark production is described in the framework of perturbative fragmentation functions, with NLO coefficient functions, NLL non-singlet DGLAP evolution and NNLL large-x resummation. We model hadronization effects by means of the effective coupling constant in the NNLO approximation and compare our results with experimental data taken at the Z0 pole and at the Upsilon(4S) resonance. We find that, within the experimental and theoretical uncertainties, our model is able to give a reasonable description of D*+-meson spectra from ALEPH for x<1-Lambda/m_c. More serious discrepancies are instead present when comparing with D and D^* data from BELLE and CLEO in x-space. Within the errors, our model is nonetheless capable of reproducing the first ten Mellin moments of all considered data sets. However, the fairly large theoretical uncertainties call for a full NNLO/NNLL analysis.Comment: 26 pages, 10 figures. Analysis in Mellin space and few references adde

    Measurement of Heavy Quark cross-sections at CDF

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    The measurement of heavy quark cross-sections provides important tests of the QCD theory. This paper reviews recent measurements of single b-quark and correlated b-quark cross-sections at CDF. Two new measurements of the single b-quark production at CDF agree with the first result from CDF Run II. This clarifies the experimental situation and confirms the recent agreement of theoretical prediction with data. A new measurement of the correlated bbˉb\bar{b} cross-section with dimuon events at CDF is presented. It agrees with theory and it does not confirm the anomalously large bbˉb\bar{b} cross-section seen in Run I by CDF and DO̸{\not {\rm O}} in dimuon events.Comment: EPS HEP2007 conference held in Mancheste

    Jets in 200 GeV p+p and d+Au collisions from the STAR experiment at RHIC

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    Full jet reconstruction in heavy-ion collisions is a promising tool for the quantitative study of properties of the dense medium produced at RHIC. Measurements of d+Au collisions are important to disentangle initial state nuclear effects from medium-induced kT broadening and jet quenching. Study of jet production and properties in d+Au in combination with similar studies in p+p is an important baseline measurement needed to better understand heavy-ion results. We present mid-rapidity inclusive jet pT spectra and di-jet correlations (kT) in 200 GeV p+p and d+Au collisions from the 2007-2008 RHIC run. We discuss the methods used to correct the data for detector effects and for background in d+Au collisions.Comment: 4 pages, 5 figures. To appear in Hot Quarks 2010 conference proceeding

    Measurements of the top-antitop production cross section at the Tevatron Run II CDF experiment using b-tagging

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    We present measurements of the top-antitop production cross section in b-tagged lepton + jets events from proton-antiproton collisions at 1.96 TeV using the CDF detector at Fermilab. B-jets are tagged with either a secondary vertex algorithm, or a soft lepton tagger that identifies muons from B hadron semileptonic decays. With Tevatron Run II data, we estimate the top-antitop signal fraction in two different ways: by estimating the various background contributions, and by fitting directly the leading jet transverse energy spectrum for the signal and background contributions. A subset of the sample with two secondary vertex tagged jets yields a production cross section consistent with the inclusive measurements. Results are consistent with a Standard Model top-antitop signal and current measurements of the top quark mass.Comment: 3 pages, 4 figures, DPF 2004 proceedin

    Phenomenological study of charm photoproduction at HERA

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    We present predictions for single inclusive distributions of charmed mesons, relevant to the HERA experiments. Our results are based upon a computation that correctly incorporates mass effects up to the next-to-leading order level, and the resummation of transverse momentum logarithms up to next-to-leading-logarithmic level. We apply the same acceptance cuts as the H1 and Zeus experiments, and compare our results to their data. We perform a study of the sensitivity of our predictions on the charm mass, \LambdaQCD, factorization scale, renormalization scale, and fragmentation parameters.Comment: 15 pages Latex; 25 figures include

    Optimal jet radius in kinematic dijet reconstruction

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    Obtaining a good momentum reconstruction of a jet is a compromise between taking it large enough to catch the perturbative final-state radiation and small enough to avoid too much contamination from the underlying event and initial-state radiation. In this paper, we compute analytically the optimal jet radius for dijet reconstructions and study its scale dependence. We also compare our results with previous Monte-Carlo studies.Comment: 30 pages, 11 figures; minor corrections; published in JHE

    Mixings, Lifetimes, Spectroscopy and Production of Heavy Flavor at the Tevatron

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    The Fermilab Tevatron offers unique opportunities to perform measurements of the heavier B hadrons that are not accessible at the Upsilon(4S) resonance. In this summary, we describe some recent heavy flavor results from the DO and CDF collaborations and discuss prospects for future measurements.Comment: To appear in Proceedings of the XXI International Symposium on lepton and Photon Interactions at High Energies, Fermilab, August 200

    The \pt spectrum of heavy quarks in photoproduction

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    We illustrate a formalism that allows to match the next-to-leading order cross section for the photoproduction of heavy quarks to the cross section obtained by resumming logarithms of \pt/m to the next-to-leading accuracy, thus giving a sensible prediction for any value of \pt. We present a comparison between our predictions and H1 and ZEUS data.Comment: 4 pages Latex; 3 figures included. Talk given at DIS01, 27 April - 1 May 2001, Bologna, Ital
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