On the frequency and temperature dependence of the conductivity near a metal-insulator transition
Finkel'shtein A. M.
The metal-insulator transition is examined for interacting electrons in a disordered system. The renormalization-group equations are derived for two cases: transitions in a magnetic field and transitions in the presence of magnetic impurities. It is shown that in the critical region the frequency or temperature dependence of the conductivity is governed by a new invariant charge z.