On chemical equilibrium in nuclear collisions

  • The data on average hadron multiplicities in central A+A collisions measured at CERN SPS are analysed with the ideal hadron gas model. It is shown that the full chemical equilibrium version of the model fails to describe the experimental results. The agreement of the data with the off-equilibrium version allowing for partial strangeness saturation is significantly better. The freeze-out temperature of about 180 MeV seems to be independent of the system size (from S+S to Pb+Pb) and in agreement with that extracted in e+e-, pp and p{\bar p} collisions. The strangeness suppression is discussed at both hadron and valence quark level. It is found that the hadronic strangeness saturation factor gamma_S increases from about 0.45 for pp interactions to about 0.7 for central A+A collisions with no significant change from S+S to Pb+Pb collisions. The quark strangeness suppression factor lambda_S is found to be about 0.2 for elementary collisions and about 0.4 for heavy ion collisions independently of collision energy and type of colliding system

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Author:Francesco BecattiniORCiDGND, Marek GaździckiORCiD, Josef Sollfrank
ArXiv Id:http://arxiv.org/abs/hep-ph/9710529
Parent Title (German):Report number: DFF 292/10/1997, IKF-HENPG/4-97, BI-TP 97/42
Series (Serial Number):IKF–HENPG (4–97)
Place of publication:Frankfurt am Main
Document Type:Working Paper
Date of Publication (online):2005/09/30
Year of first Publication:1997
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2005/09/30
Page Number:24
später: The European Physical Journal C - Particles and Fields, 5.1998, S. 143- 153
Source:Eur.Phys.J. C5 (1998), http://arxiv.org/abs/hep-ph/9710529
Institutes:Physik / Physik
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoDeutsches Urheberrecht