Dilepton Production in Transport-based Approaches
  We investigate dilepton production in transport-based approaches and show that the baryon couplings of the $\rho$ meson represent the most important ingredient for understanding the measured dilepton spectra. At SIS energies, the baryon resonances naturally play a major role and affect already the vacuum spectra via Dalitz-like contributions, which can be captured well in transport simulations. Recent pion-beam measurements at GSI will help to constrain the properties of the involved resonances further. 
Janus Weil, Stephan Endres, Hendrik van Hees, Marcus Bleicher, Ulrich   Mosel
nucl-th hep-ph nucl-ex