Effect of resonances on diffusive scatteringx

The presence of resonances modifies the passage of light or of electrons through a disordered medium. We generalize random-matrix theory to account for this effect. Using supersymmetry, we calculate analytically the mean density of states and the effective Lagrangian of the generating functional for the two-point function. We show that the diffusion constant scales with the effective mean level spacing. The latter exhibits a resonance dip. These facts allow us to interpret experimental results on light scattering for different concentrations of resonant scatterers.