These proceedings present recent results from transport-hydrodynamics-hybrid models for heavy ion collisions at relativistic energies. The main focus is on the absorption of (anti-)protons in the hadronic afterburner stage of the reaction, di-lepton production at SPS and heavy quark dynamics.
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 nat
urally 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.
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 low energies (of a few GeV), the baryon
resonances naturally play a larger role and affect already the vacuum spectra via Dalitz-like contributions, which can be captured well in an on-shell-transport scheme. At higher energies, the baryons mostly affect the in-medium self energy of the $rho$, which is harder to tackle in transport models and requires advanced techniques.
