Strangeness in Nuclear Collisions

TL;DR

This paper compiles data on strange hadron production in various nuclear collisions, revealing energy-dependent behaviors and supporting the hypothesis of Quark Gluon Plasma formation at SPS energies based on statistical analysis.

Contribution

It provides a comprehensive analysis of strange particle multiplicities across different collision systems and energies, suggesting the onset of Quark Gluon Plasma formation between AGS and SPS energies.

Findings

Strangeness to pion ratio increases with energy in nucleon-nucleon collisions.

Ratio saturates with nuclear mass at AGS energies.

Significant change in behavior indicates QGP formation between AGS and SPS.

Abstract

Data on the mean multiplicity of strange hadrons produced in minimum bias proton--proton and central nucleus--nucleus collisions at momenta between 2.8 and 400 GeV/c per nucleon have been compiled. The multiplicities for nucleon--nucleon interactions were constructed. The ratios of strange particle multiplicity to participant nucleon as well as to pion multiplicity are larger for central nucleus--nucleus collisions than for nucleon--nucleon interactions at all studied energies. The data at AGS energies suggest that the latter ratio saturates with increasing masses of the colliding nuclei. The strangeness to pion multiplicity ratio observed in nucleon--nucleon interactions increases with collision energy in the whole energy range studied. A qualitatively different behaviour is observed for central nucleus--nucleus collisions: the ratio rapidly increases when going from Dubna to AGS energies and changes little between AGS and SPS energies. This change in the behaviour can be related to the increase in the entropy production observed in central nucleus-nucleus collisions at the same energy range. The results are interpreted within a statistical approach. They are consistent with the hypothesis that the Quark Gluon Plasma is created at SPS energies, the critical collision energy being between AGS and SPS energies.