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HK: Physik der Hadronen und Kerne

HK 43: Theorie VIII

HK 43.1: Gruppenbericht

Donnerstag, 22. März 2001, 14:30–15:00, B

Probing the nuclear equation of state by K⁺ production in heavy ion collisions — •Christian Fuchs¹, Salim El-Basaouny¹, Amand Faessler¹, Eugene Zabrodin¹, and Yu-Ming Zheng² — ¹Institut fuer Theoretische Physik, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen, Germany — ²China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413, China

The dependence of K⁺ production on the nuclear equation of state is investigated in heavy ion collisions. An increase of the excitation function of K⁺ multiplicities obtained in heavy (Au+Au) over light (C+C) systems when going far below threshold has been observed by the KaoS Collaboration [1]. Model calculations within the QMD transport approach can reproduce this observable, i.e. the excitation function of the kaon multiplicities in (Au+Au)/(C+C) and demonstrate that it is quite robust against possiblly existing theoretical uncertainties of the calculations. The comparision to data strongly favours a soft equation of state [2]. This observation holds despite of the influence of an in-medium kaon potential predicted by effective chiral models which is necessary to reproduce the experimental K⁺ yields.

[1] C. Sturm et al., Phys. Rev. Lett. in press.

[2] C. Fuchs et al., Phys. Rev. Lett. submitted