Strange particle production from SIS to LHC

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, e.g. the different centrality dependences of pions and kaons. Furthermore, the independence of theK ⁺ toK ^- ratio on the number of participating nucleons observed between SIS and relativistic heavy-ion collider (RHIC) is consistent with this model. The observed maximum in theK ⁺/π⁺ excitation function is also seen in the ratio of strange to non-strange particle production. The appearance of this maximum around 30 A.GeV is due to the energy dependence of the chemical freeze-out parametersT and μ_B.