Kaon and pion production in relativistic heavy-ion collisions

Abstract

The Boltzmann-Uehling-Uhlenbeck (BUU) transport model is applied to study strangeness and pion production in nucleus-nucleus collisions. Starting from proton induced reactions, we further investigate $\mathrm{Si}+\mathrm{Au},\mathrm{Au}+\mathrm{Au}$, and $\mathrm{Pb}+\mathrm{Pb}$ collisions in the energy range between 2 and $40A\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}$ and compare the results with data and other transport calculations. The $q\overline{q}$-annihilation, or resonance, channel simulated by the string model in meson-nucleon collisions at $\sqrt{s}>2\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}$ is introduced. The importance of this channel for a good description of the proton-nucleus data on ${K}^{+}$ production is demonstrated. We further show that meson-meson collisions contribute significantly to the $K\stackrel{\underline{}}{K}$ production in heavy-ion collisions above $5A\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}$ and improve the agreement with data on the ${K}^{+}/{\ensuremath{\pi}}^{+}$ ratio. Finally, we study the influence of in-medium modifications of the FRITIOF model on pion and kaon production.