204 research outputs found

    Linear Extrapolation of Ultrarelativistic Nucleon-Nucleon Scattering to Nucleus-Nucleus Collisions

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    We use a Glauber-like approach to describe very energetic nucleus-nucleus collisions as a sequence of binary nucleon-nucleon collisions. No free parameters are needed: all the information comes from simple parametrizations of nucleon-nucleon collision data. Produced mesons are assumed not to interact with each other or with the original baryons. Comparisons are made to published experimental measurements of baryon rapidity and transverse momentum distributions, negative hadron rapidity and transverse momentum distributions, average multiplicities of pions, kaons, hyperons, and antihyperons, and zero degree energy distributions for sulfur-sulfur collisions at 200 GeV/c per nucleon and for lead-lead collisions at 158 GeV/c per nucleon. Good agreement is found except that the number of strange particles produced, especially antihyperons, is too small compared with experiment. We call this model LEXUS: it is a baseline linear extrapolation of ultrarelativistic nucleon-nucleon scattering to heavy ion collisions.Comment: 37 pages, 15 figures, LaTeX, uses rotating.st

    Charge Transfer Fluctuations as a Signal for QGP

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    In this work, the charge transfer fluctuation which was previously used for pppp collisions is proposed for relativistic heavy-ion collisions as a QGP probe. We propose the appearance of a local minimum at midrapidity for the charge transfer fluctuation as a signal for a QGP. Within a two-component neutral cluster model, we demonstrate that the charge transfer fluctuation can detect the presence of a QGP as well as the size of the QGP in the rapidity space. We also show that the forward-backward correlation of multiplicity can be a similarly good measure of the presence of a QGP. Further, we show that the previously proposed net charge fluctuation is sensitive to the existence of the second phase only if the QGP phase occupies a large portion of the available rapidity space.Comment: 15 pages, 14 figures, to be submitte

    A statistical model analysis of yields and fluctuations in 200 GeV Au-Au collisions

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    We show that the simultaneous measurement of yields and fluctuations is capable of falsifying and constraining the statistical hadronization model. We show how such a measurement can test for chemical non-equilibrium, and distinguish between a high temperature chemically equilibrated freeze-out from a supercooled freeze-out with an over-saturated phase space. We perform a fit, and show that both yields and fluctuations measured at RHIC 200 GeV can be accounted for within the second scenario, with both the light and strange quark phase space saturated significantly above detailed balance. We point to the simultaneous fit of the K/πK/\pi fluctuation and the K/KK^*/K^- ratio as evidence that the effect of hadronic re-interactions after freeze-out is small.Comment: Poster proceedings, QM2005 conference, Budapes