### arXiv:nucl-ex/0202003AbstractReferencesReviewsResources

#### Survey of experimental data

Published 2002-02-06Version 1

>A review of meson emission in heavy ion collisions at incident energies from SIS up to collider energies is presented. A statistical model assuming chemical equilibrium and local strangeness conservation (i.e. strangeness conservation per collision) explains most of the observed features. Emphasis is put onto the study of $K^+$ and $K^-$ emission at low incident energies. In the framework of this statistical model it is shown that the experimentally observed equality of $K^+$ and $K^-$ rates at ``threshold-corrected'' energies $\sqrt{s} - \sqrt{s_{th}}$ is due to a crossing of two excitation functions. Furthermore, the independence of the $K^+/K^-$ ratio on the number of participating nucleons observed between SIS and RHIC is consistent with this model. It is demonstrated that the $K^-$ production at SIS energies occurs predominantly via strangeness exchange and that this channel is approaching chemical equilibrium. The observed maximum in the $K^+/\pi^+$ excitation function is also seen in the ratio of strange to non-strange particle production. The appearance of this maximum around 30 $A\cdot$GeV is due to the energy dependence of the chemical freeze-out parameters $T$ and $\mu_B$.

**Comments:**13 pages, 14 figures, SQM2001 in Frankfurt, Sept. 2001, submitted to IOP

**Journal:**J.Phys.G28:1787-1800,2002

**Categories:**nucl-ex

**Keywords:**experimental data, model assuming chemical equilibrium, excitation function, local strangeness conservation, sis energies occurs

**Tags:**journal article

*et al.*