The time evolution of vector-meson spectral-functions is studied within a kinetic theory approach. We implement this formalism in a BUU type transport model. Applications focus on ρ and ɷ mesons being important pieces for the interpretation of the di-electron invariant mass spectrum measured by the HADES collaboration for the reaction C + C at 2 AGeV bombarding energy. Since the evolution of the spectral functions is driven by the local density, the in-medium modifications are tiny for small collision systems within this approach, as the life time of the compressed stage is too short.
PACS numbers: 21.65.+f, 24.10.Cn, 24.10.Jv, 26.60.+C