Statistical Model Description of $K^{+}$ and $K^{-}$ Production between 1 - 10 AGeV

Abstract

The excitation functions of $K^{+}$ and $K^{-}$ mesons in heavy ion collisions are studied within a statistical model assuming chemical and thermal equilibrium with exact strangeness conservation. At low incident energies the associate production of kaons, i.e. the production of a K+ together with a hyperon and the production of a K- together with a K+, implies specific features: different threshold energies and different dependences of K+ and K- yields on baryon number density. It is shown that the experimentally observed equality of the $K^{+}$ and $K^{-}$ rates at energies $\sqrt{s}-\sqrt{s_{th}}\le 0$ is due to a crossing of the two excitation functions. Furthermore, the independence of the $K^{+}$ to $K^{-}$ ratio on the number of participating nucleons observed at 1 and 10 $A\cdot$GeV is consistent with this model.

Comments: 3 Postscript figures, uses elsart.sty