Heidelberg 2015 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 53: Heavy Ion Collisions and QCD Phases 6

HK 53.4: Vortrag

Donnerstag, 26. März 2015, 15:30–15:45, T/HS1

Deep sub-threshold strangeness production in nuclear collisions with the UrQMD transport model — •Jan Steinheimer¹, Gunnar Graef¹, Feng Li³, and Marcus Bleicher^1,2 — ¹FIAS, Frankfurt am Main — ²ITP, Goethe Universität, Frankfurt am Main — ³Texas A&M University, College Station, USA

I will present results on deep sub threshold strangeness production in nuclear collisions, with the UrQMD transport model. Introducing anti-kaon+baryon and hyperon+hyperon strangeness exchange reactions we obtain a good description of experimental data on single strange hadron production in Ar+KCl reactions at E_lab=1.76 A GeV. We find that the hyperon strangeness exchange is the dominant process contributing to the Ξ⁻ yield, however remains short of explaining the large Ξ⁻/Λ ratio measured with the HADES experiment while agreeing well with a thermal fit to the data. I will further discuss open problems in the microscopic description of strangess production at SIS18 energies, including the surprisingly high φ/K⁻ ratio measured with the HADES experiment as well as uncertainties arising from unknown resonance branching ratios.