Medium effects in ρ-meson photoproduction

We compute dilepton invariant mass spectra from the decays of ρ mesons produced by photon reactions off nuclei. Our calculations employ a realistic model for the ρ photoproduction amplitude on the nucleon which provides fair agreement with measured cross sections. Medium effects are implemented via an earlier constructed ρ propagator based on hadronic many-body theory. At incoming photon energies of 1.5-3 GeV as used by the CLAS experiment at JLAB, the average density probed for iron targets is estimated at about half saturation density. At the pertinent 3-momenta the predicted medium effects on the ρ propagator are rather moderate. The resulting dilepton spectra approximately agree with recent CLAS data.