Comparison of strangeness production between A+A and p+p reactions from 2 to 160A GeV

The measured K⁺/π⁺ ratios from heavy-ion reactions are compared with the K⁺/π⁺ ratios from p+p reactions over the energy range 2-160A GeV. The K/π enhancement in heavy-ion reactions is largest at the lower energies, consistent with strangeness production in secondary scattering becoming relatively more important than initial collisions near the kaon production threshold. The enhancement decreases steadily from 4 to 160A GeV, suggesting that the same enhancement mechanism of hadronic rescattering and decay of strings may be applicable over this full energy range. Based on existing data, the midrapidity K⁺/π⁺ ratio is predicted to be 0.25±0.02 for the forthcoming Pb+Pb reactions at 40A GeV/c.