2,347 research outputs found

    A simple model for transverse energy distribution in heavy ion collisions

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    A simple geometrical model (often quoted in literature as the Glauber model) of heavy ion collisions is recapitulated. It is shown that the transverse energy distribution of heavy ion collisions follow the geometry of the collision. An extension of the model to include rapidity and transverse mass particle spectra is discussed.Comment: 7 page

    Quark Matter 99 Summary: Hadronic Signals

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    I review the new data presented at QM99. The main emphasis is placed on the CERN SPS hadron production systematics concluding that the boundary between a partonic and a hadronic phase has now been located at T=180±10 MeVT=180 \pm10\:MeV and ϔ≈1 GeV\epsilon \approx 1 \:GeV per fm3fm^3.Comment: 18 page

    Clocking hadronization in relativistic heavy ion collisions with balance functions

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    A novel state of matter has been hypothesized to exist during the early stage of relativistic heavy ion collisions, with normal hadrons not appearing until several fm/c after the start of the reaction. To test this hypothesis, correlations between charges and their associated anticharges are evaluated with the use of balance functions. It is shown that late-stage hadronization is characterized by tightly correlated charge/anticharge pairs when measured as a function of relative rapidity.Comment: 5 pages, 3 figure

    Measurement of D-meson production at mid-rapidity in pp collisions at √s=7 TeV

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    The production cross sections for prompt charmed mesons D0, D+, D∗+ and D+s were measured at mid-rapidity in proton–proton collisions at a centre-of-mass energy √s=7 TeV with the ALICE detector at the Large Hadron Collider (LHC). D mesons were reconstructed from their decays D0→K−π+, D+→K−π+π+, D∗+→D0π+, D+s→ϕπ+→K−K+π+, and their charge conjugates.With respect to previous measurements in the same rapidity region, the coverage in transverse momentum (pT) is extended and the uncertainties are reduced by a factor of about two. The accuracy on the estimated total ccbar production cross section is likewise improved. The measured pT-differential cross sections are compared with the results of three perturbative QCD calculations.<br/

    Recent developments on the ALICE central Trigger processor

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    The ALI CE Central Trigger Processor has been constructed and tested, and will shortly be installed in the experimental area. In this review, we introduce the new developments in hardware and software, present a measurement of the minimum propagation time, and illustrate various trigger applications

    Strangeness Content in the Nucleon

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    I review recent studies of strangeness content in the nucleon pertaining to the flavor-singlet gA0g_A^0, the sˉs\bar{s}s matrix element and the strangeness electric and magnetic form factors GEs(q2)G_E^s(q^2) and GMs(q2)G_M^s(q^2), based on lattice QCD calculations. I shall also discuss the relevance of incorporating the strangeness content in nuclei in regard to strange baryon-antibaryon productions from proton-nucleus and nucleus-nucleus collisions at SPS and RHIC energies.Comment: 11 pages, 4 figures, Invited talk at V Int. Conf. on Strangeness in Quark Matter, Berkeley, CA, July 20--25, 200

    Strangeness enhancement from strong color fields at RHIC

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    In ultra-relativistic heavy ion collisions, early stage multiple scatterings may lead to an increase of the color electric field strength. Consequently, particle production - especially heavy quark (and di-quark) production - is greatly enhanced according to the Schwinger mechanism. We test this idea via the Ultra-relativistic Quantum Molecular Dynamics model (UrQMD) for Au+Au collisions at the full RHIC energy (s=200\sqrt{s} = 200 AGeV). Relative to p+p collisions, a factor of 60, 20 and 7 enhancement respectively, for Ω\Omega (ssssss), Ξ\Xi (ssss), and Λ\Lambda, ÎŁ\Sigma (ss) is predicted for a model with increased color electric field strength
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