The nuclear equation of state probed by $K^{+}$ production in heavy ion collisions

Abstract

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 which has been observed by the KaoS Collaboration strongly favours a soft equation of state. 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. Phase space effects are discussed with respect to the $K^{+}$ excitation function.

Comments: 14 pages Revtex, 6 figures, Proceedings to the XXXIX Interantional Winter Meeting on Nuclear Physics, Bormio, Italy, 2001