Density dependence of resonance broadening and shadowing effects in   nuclear photoabsorption
  Medium effects as a function of the mass number $A$ are studied in the total photonuclear cross section from the $\Delta$-resonance region up to the region where shadowing effects are known to exist. A consistent picture is obtained by simply assuming a density dependence of the different mechanisms of resonance broadening and shadowing. The $\Delta$-mass shift is found to increase with $A$. 
S. Boffi, Ye. Golubeva, L.A. Kondratyuk, M.I. Krivoruchenko and E.   Perazzi