Systematic study of the kaon to pion multiplicity ratios in heavy-ion collisions

We present a systematic study of the kaon to pion multiplicity ratios ${(K}^{+}/{\pi }^{+}$ and $K^{-}/{\pi }^{-})$ in heavy-ion collisions from AGS to RHIC energy using the relativistic quantum molecular dynamics (RQMD) model. The model describes reasonably well the available experimental data on $K^{+}/{\pi }^{+}$ and $K^{-}/{\pi }^{-}.$ Within the model, we find that the strong increase of the ratios with the number of participants is mainly due to hadronic rescattering of produced mesons with ingoing baryons and their resonances. The enhancement of $K/\pi$ in heavy-ion collisions with respect to elementary $p+p$ interactions is larger at AGS than SPS energy, and decreases smoothly with bombarding energy. The total multiplicity ratios at RHIC energy are predicted by RQMD to be $K^{+}/{\pi }^{+}=0.19\mathrm{}$ and $K^{-}/{\pi }^{-}=\mathrm{0.15.}\mathrm{}$