Gießen 2007 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 26: Physik mit schweren Ionen
HK 26.2: Talk
Wednesday, March 14, 2007, 11:30–11:45, F
Multiplicity fluctuations in relativistic nuclear collisions: statistical model versus experimental data — Victor Begun1,2, Marek Gazdzicki3,4, Mark Gorenstein2,5, •Michael Hauer6,7, Volodya Konchakovski2,6, and Benjamin Lungwitz3 — 1Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, Rome, Italy — 2Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine — 3Institut für Kernphysik, University of Frankfurt, Frankfurt, Germany — 4Swicetokrzyska Academy, Kielce, Poland — 5Frankfurt Institute for Advanced Studies, Frankfurt,Germany — 6Helmholtz Research School, University of Frankfurt, Frankfurt, Germany — 7University of Cape Town, Cape Town, South Africa
The multiplicity distributions of hadrons produced in central nucleus-nucleus collisions are studied within the hadron-resonance gas model in the large volume limit. The multiplicity distributions and the scaled variances for negatively, positively, and all charged hadrons are calculated along the chemical freeze-out line of central Pb+Pb (Au+Au) collisions from SIS to LHC energies. Predictions obtained within different statistical ensembles are compared with the preliminary NA49 experimental results on central Pb+Pb collisions in the SPS energy range. The measured fluctuations are significantly narrower than the Poisson ones and clearly favor expectations for the micro-canonical ensemble. Thus this is a first observation of the recently predicted suppression of the multiplicity fluctuations in relativistic gases in the thermodynamical limit due to conservation laws.