Mass shift, width broadening and spectral density of ρ-mesons produced in heavy ion collisions

Abstract Modifications of ρ-mesons formed at the last stage of evolution of hadronic matter produced in heavy ion collisions are studied. It is found that while the mass shift is on the order of a few tens of MeV, the width and spectral density become so broad that ρ may lose its identity as a well defined resonance.