We present a detailed analytical and numerical analysis of the inelastic coherent backscattering spectrum of laser light incident on cold atoms. We identify frequency domains where the interference contribution can be positive \emph{as well as} negative -- or exhibits dispersive character. These distinctive features are explained by reciprocity arguments and dressed state two-photon scattering amplitudes.
@article{arxiv.0801.0119,
title = {Spectrum of coherently backscattered light from two atoms},
author = {Vyacheslav Shatokhin and Thomas Wellens and Benoît Grémaud and Andreas Buchleitner},
journal= {arXiv preprint arXiv:0801.0119},
year = {2009}
}