INFLUENCE OF THE IN-MEDIUM PION DISPERSION-RELATION IN HEAVY-ION COLLISIONS

We investigate the influence of medium corrections to the pion dispers ion relation on the pion dynamics in intermediate energy heavy ion col lisions. To do so a pion potential is extracted from the in-medium dis persion relation and used in QMD calculations and thus we take care of both, real and imaginary part of the pion optical potential. The pote ntials are determined from different sources, i.e., from the Delta-hol e model and from phenomenological approaches. Depending on the strengt h of the potential, a reduction of the anticorrelation of pion and nuc leon flow in noncentral collisions is observed as well as an enhanceme nt of the high-energetic yield in transverse pion spectra. A compariso n to experiments, in particular to p(t) spectra for the reaction Ca+Ca at 1 GeV/nucleon and the pion in-plane flow in Ne+Pb collisions at 80 0 MeV/nucleon, generally favors a weak potential.