Resonance studies in heavy ion collisions: a critical overview

In order to probe different stages of a heavy ion collision, resonances have proven to be a unique tool. Due to rescattering effects resonance studies using hadronic decay products are ideal in order to probe the late stage of a heavy ion collision, i.e. close to freeze-out. Recent studies also have shown that such analyses can give an estimate about the time span between chemical and kinetic freeze-out. On the contrary, resonances that decay into di-leptons probe the integrated collision, since the leptonic decay products do not interact with the hadronic medium. When comparing both approaches one can learn something about the early phase and extract informations about in-medium modifications of e.g. vector mesons. In this talk an overview about various resonance and dilepton studies within a transport approach and statistical models is given. The main focus will be on the highest RHIC energy of √(s) = 200 AGeV. (orig.)