The inconstant world of composite excitons

The composite nature of the exciton gives rise to very many carrier exchanges which cannot be accounted correctly through an effective Hamiltonian for bosonized particles. This forced us to construct a new many-body procedure [For a short review, see M. Combescot, O. Betbeder-Matibet, Solid State Commun. 134 (2005) 11]. Here we report a few important aspects of this procedure, using Shiva diagrams [M. Combescot, O. Betbeder-Matibet, Eur. Phys. J. B 55 (2007) 63] which greatly help not only to visualize, but also to calculate the subtle carrier exchanges which take place between composite excitons.