Strangeness dynamics in relativistic nucleus-nucleus collision

  • We investigate hadron production as well as transverse hadron spectra in nucleus-nucleus collisions from 2 A.GeV to 21.3 A.TeV within two independent transport approaches (UrQMD and HSD) that are based on quark, diquark, string and hadronic degrees of freedom. The comparison to experimental data demonstrates that both approaches agree quite well with each other and with the experimental data on hadron production. The enhancement of pion production in central Au+Au (Pb+Pb) collisions relative to scaled pp collisions (the 'kink') is well described by both approaches without involving any phase transition. However, the maximum in the K+/Pi+ ratio at 20 to 30 A.GeV (the 'horn') is missed by ~ 40%. A comparison to the transverse mass spectra from pp and C+C (or Si+Si) reactions shows the reliability of the transport models for light systems. For central Au+Au (Pb+Pb) collisions at bombarding energies above ~ 5 A.GeV, however, the measured K +/- m-theta-spectra have a larger inverse slope parameter than expected from the calculations. The approximately constant slope of K+/-spectra at SPS (the 'step') is not reproduced either. Thus the pressure generated by hadronic interactions in the transport models above ~ 5 A.GeV is lower than observed in the experimental data. This finding suggests that the additional pressure - as expected from lattice QCD calculations at finite quark chemical potential and temperature - might be generated by strong interactions in the early pre-hadronic/partonic phase of central Au+Au (Pb+Pb) collisions.

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Author:Elena L. BratkovskayaORCiDGND, Marcus BleicherORCiDGND, Wolfgang CassingGND, Marco van LeeuwenORCiDGND, Manuel Reiter, Sven SoffORCiD, Horst StöckerORCiDGND, Henning WeberGND
Parent Title (English):Progress in particle and nuclear physics
Publisher:Pergamon Press
Place of publication:Oxford [u. a.] ; Frankfurt, M.
Document Type:Article
Date of Publication (online):2005/04/13
Year of first Publication:2004
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2005/04/13
Tag:Meson production; Particle and resonance production; Quark gluon plasma; Relativistic heavy-ion collisions
Page Number:13
First Page:225
Last Page:237
© 2004 Elsevier B.V. All rights reserved.
Source: , Invited talk presented by H. Stöcker at ERICE-2003 (Sep. 2003, Erice, Italy), to be published in Prog. Part. Nucl. Phys.
Institutes:Physik / Physik
Wissenschaftliche Zentren und koordinierte Programme / Helmholtz International Center for FAIR
Wissenschaftliche Zentren und koordinierte Programme / Frankfurt Institute for Advanced Studies (FIAS)
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht