Energy dependence of hyperon production in nucleus–nucleus collisions at SPS

A measurement of strange baryon and antibaryon production in Pb–Pb collisions has been carried out by the NA57 experiment at the CERN SPS, with 40 and 158 A GeV/c beam momentum. Results on Λ, Ξ and Ω hyperon yields at mid-rapidity in the most central 53% of Pb–Pb collisions at 40 A GeV/c are presented and compared with those obtained at higher energy, in the same collision centrality range. The Λ and Ξ− yields per unit rapidity stay roughly constant while those of Ω−, Λ̄, Ξ̄+ and Ω̄+ increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in sNN=130 GeV Au–Au collisions at RHIC.