Strangeness Production in Heavy Ion Collisions at SPS Energies

TL;DR

This paper reports on measurements of strange particle production in central Pb-Pb collisions across a range of energies at SPS, revealing energy-dependent patterns in particle ratios and hyperon yields.

Contribution

It provides new experimental data on strangeness production at SPS energies, including multi-strange hyperons, and compares these results with other energy regimes.

Findings

K+/π+ and Λ/π ratios peak around 30 A·GeV.

K-/π- and Λ̄/π ratios increase continuously with energy.

φ/π ratio rises monotonically with beam energy.

Abstract

The NA49 collaboration has taken data of central Pb-Pb collisions at beam energies from 20 to 158 GeV per nucleon. The large acceptance of the detector allows to study particle yields in full phase space. In this paper we present recent results on strangeness production (K, $\Lambda$ and $\phi$) in this energy range and compare to measurements at lower and higher energies. The K$^+/\pi^+$ and $\Lambda/\pi$ ratio shows a pronounced maximum around 30 A$\cdot$GeV, whereas the K$^-/\pi^-$ and $\bar{\Lambda}/\pi$ ratio exhibits a continuous rise. The $\phi/\pi$ ratio also increases monotonically with beam energy. First results on multi-strange hyperon production at lower SPS energies are presented.