Eta and dilepton production in heavy-ion reactions

We present a nonperturbative dynamical study of η-meson and pion production in heavy-ion collisions from 1 to 2 GeV/A bombarding energy. The dynamical evolution of the nucleus-nucleus collision is described by a transport equation of the Boltzmann-Uehling-Uhlenbeck type. Our model evolves phase-space distribution functions for nucleons, Δ's, N(1440)'s, N(1535)'s, pions and η's with their isospin degrees of freedom. Furthermore, we show results for dilepton yields in heavy-ion collisions at bombarding energies of 1 and 2 GeV/A. All known sources of dileptons are taken into account. We investigate in particular the sensitivity of the calculated yields to predicted changes of the ρ meson in dense matter and discuss the feasibility to measure the time-like electromagnetic form factor of hadrons and their medium-dependence through the observation of dileptons. (orig.)