Dilepton production in proton-induced reactions at SIS energies with the   GiBUU transport model
  We present dilepton spectra from p+p, d+p and p+Nb reactions at SIS energies, which were simulated with the GiBUU transport model in a resonance model approach. These spectra are compared to the data published by the HADES and DLS collaborations. It is shown that the $\rho$ spectral function includes non-trivial effects already in elementary reactions, due to production via baryon resonances, which can yield large contributions to the dilepton spectrum. Dilepton spectra from nuclear reactions in the energy range of the HADES experiment are thus found to be sensitive also to properties of nucleon resonances in the nuclear medium. 
Janus Weil, Hendrik van Hees, Ulrich Mosel
nucl-th hep-ph nucl-ex