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 $\Lambda$, $\Xi$ and $\Omega$ 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 $\Lambda$ and ${\Xi }^{-}$ yields per unit rapidity stay roughly constant while those of ${\Omega }^{-}$, $\bar{\Lambda }$, ${\bar{\Xi }}^{+}$ and ${\bar{\Omega }}^{+}$ increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in $\sqrt{s_{NN}}$ = 130 GeV Au-Au collisions at RHIC.

9 pages, 4 figures, 3 tables, accepted for publication in Physics Letters B