An effective theory for conductance by symmetry breaking
  An effective theory is suggested for the particle-anti particle and the particle-particle modes of strongly disordered electron systems. The effective theory is studied in the framework of the saddle point expansion and found to support a vacuum which is not invariant under translations in imaginary time. The Goldstone bosons of this symmetry breaking generate a pole in the density-density correlation function. The condensate of the auxiliary field corresponding to the particle-particle channel produces conductivity without relying on the long range fluctuations. The results are obtained for $d>1$. 
Sebastiao Correia, Janos Polonyi, Jean Richert