Catalytic ϕ meson production in heavy-ion collisions

Abstract

The phi meson production on hyperons πY → ϕY and anti-kaons is argued to be a new efficient source of phi mesons in a nucleus–nucleus collision. These reactions are not suppressed according to the Okubo–Zweig–Izuka rule in contrast to the processes with non-strange particles in the entrance channels, πB and BB with B = N, Δ. A rough estimate of the cross sections within a simple hadronic model shows that the cross sections of πY → ϕY and reactions can exceed that of the πN → ϕN reaction by factors 50 and 60, respectively. In the hadrochemical model for nucleus–nucleus collisions at SIS and lower AGS energies, we calculate the evolution of strange particle populations and the ϕ meson production rate due to the new processes. It is found that the catalytic reactions can be operative if the maximal temperature in nucleus–nucleus collisions is larger than 130 MeV and the collision time is larger than 10 fm. A possible influence of the catalytic reactions on the centrality dependence of the ϕ yield at AGS energies and the ϕ rapidity distributions at SPS energies is discussed.