Strangeness production at SPS energies in a (3+1)-dimensional Boltzmann+hydrodynamics approach

J Steinheimer (1) , H Petersen (2) , M Mitrovski (3) , M Bleicher (3)

1 Institut für Theoretische Physik
2 Department of Physics
3 Frankfurt Institute for Advanced Studies

Results on strange particle production at energies from √ s = 2 − 200 A GeV from a (3+1)dimensional Boltzmann+hydrodynamics hybrid model are presented and compared to results from the Ultra-relativistic Quantum Molecular Dynamics transport approach and existing experimental data. The hybrid model with an intermediate hydrodynamical evolution for the hot and dense stage of the collision allows us to explore the centrality and system size dependence of (multi-strange) hyperon production in A+A collisions. The transition from a system which is not fully thermalized, like in C+C or Si+Si collisions, to supposedly fully thermalized systems as e.g. created in Pb+Pb reactions is investigated. The hyperon yields are enhanced in the hybrid approach due to the local equilibrium assumption and therefore in line with the experimental data. The excitation functions of strange to nonstrange particle yields (e.g. K + /π +) calculated in the hybrid approach are able to reproduce the famous 'horn ' structure at SPS energies with a purely hadronic equation of state in contrast to the pure transport approach, which failed to explain the experimental data.

Mots clés: Physical Sciences

J Steinheimer, H Petersen, M Mitrovski, M Bleicher. Strangeness production at SPS energies in a (3+1)-dimensional Boltzmann+hydrodynamics approach. Journal of Physics G: Nuclear and Particle Physics, 2010, 37 (9), pp.94038. ⟨10.1088/0954-3899/37/9/094038⟩. ⟨hal-00600848⟩