Low-mass dileptons and dropping rho meson mass
  Using the transport model, we have studied dilepton production from heavy-ion collisions at Bevalac energies. It is found that the enhanced production of low-mass dileptons observed in the experiment by the DLS collaboration cannot be explained by the dropping of hadron masses, in particular the $\rho$-meson mass, in dense matter. 
E. L. Bratkovskaya (Giessen U.) and C. M. Ko (Texas A&M U.)