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

Abstract 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 hyperonyields 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 − , Λ , Ξ + and Ω + increase when going to the higher SPS energy. Hyperonyields at the SPS are compared with those from the STAR experiment in s NN =130 GeV Au–Au collisions at RHIC.