Some remarks on the electronic states in disordered materials

Recalls how the field theory formalism is very useful for computing the density of electronic levels in disordered materials, and stresses those characteristics of the associated field theory which are peculiar to this model. In particular, the author shows that the localisation transition associated with the mobility edge has rather strange properties from the point of view of pure field theory: a sound computation of the critical exponents associated with the mobility edge is rather difficult, due to this unusual behaviour.