We develop a perturbative treatment of induced dipole-dipole interactions in
the diffusive transport of electromagnetic waves through disordered atomic
clouds. The approach is exact at order two in the atomic density and accounts
for the vector character of light. It is applied to the calculation of the
electromagnetic energy stored in the atomic cloud - which modifies the energy
transport velocity - and of the light scattering and transport mean free paths.
Results are compared to those obtained from a purely scalar model for light.Comment: revised versio