Laboratoire de Physique Théorique
Toulouse - UMR 5152

This work was inspired by heated debates around the issue of zero-temperature decoherence in disordered conductors ca. 2000 : according to some authors, the electron dephasing rate in a disordered metal could tend to a finite non-zero value in the zero-temperature limit. Not only this sounded spectacular, it also appeared that some experiments were lending support to the statement. I wondered whether one could answer the question based only on general arguments. Even though I failed, there was a consolation prize at the end — the understanding of how the diffusion pole in the density propagator stems directly from gauge invariance :

RR, Phys. Rev. B 66, 220503 (2002)