Scaling of deuteron production in ultrarelativistic nucleus-nucleus collisions

Deuteron production in S- and Pb-induced collisions at ultrarelativistic energies is studied in a transport model, treating the deuteron production by phase space coalescence. The production rate of deuterons as a function of rapidity, dNddy, is approximately found to satisfy a simple scaling behavior in terms of the proton and the pion rapidity distributions, dNpdy and dNπdy, namely dNddy ∼ (dNpdy)2/(dNπdy). The scaling is a consequence of the near equality of the freeze-out volumes the nucleons and mesons. Violation of the scaling is attributed to differences between these freeze-out volumes.