Particle ratios from AGS to RHIC in an interacting hadronic model

  • Abstract: The measured particle ratios in central heavy-ion collisions at RHIC-BNL are investigated within a chemical and thermal equilibrium chiral SU(3) Ã É approach. The commonly adopted non-interacting gas calculations yield temperatures close to or above the critical temperature for the chiral phase transition, but without taking into account any interactions. In contrast, the chiral SU(3) model predicts temperature and density dependent effective hadron masses and effective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. Three different parametrizations of the model, which show different types of phase transition behaviour, are investigated. We show that if a chiral phase transition occured in those collisions, freezing of the relative hadron abundances in the symmetric phase is excluded by the data. Therefore, either very rapid chemical equilibration must occur in the broken phase, or the measured hadron ratios are the outcome of the dynamical symmetry breaking. Furthermore, the extracted chemical freeze-out parameters differ considerably from those obtained in simple non-interacting gas calculations. In particular, the three models yield up to 35 MeV lower temperatures than the free gas approximation. The inmedium masses turn out to differ up to 150 MeV from their vacuum values.

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Author:Detlef ZschiescheGND, Gebhard Zeeb, Kerstin Paech, Horst StöckerORCiDGND, Stefan SchrammGND
Parent Title (German):Journal of Physics G: Nuclear and Particle Physics
Document Type:Article
Year of Completion:2003
Date of first Publication:2003/12/11
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2005/11/09
Tag:Gleichgewicht; Kollisionen des schweren Ions; Partikel; hadronic
equilibrium; hadronic; heavy-ion collisions; particle ratios
First Page:S381
Last Page:S391
Institutes:Physik / Physik
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