Effect of Disorder on Charge Density Wave and Superconducting Order in   the Half-Filled Attractive Hubbard Model
  The half-filled attractive Hubbard model exhibits simultaneous charge density wave and superconducting order in its ground state. In this paper we explore the effect of disorder in the site energies on this degeneracy. We find that superconducting order survives randomness out to a critical amount of disorder, but charge ordering is immediately reduced. We explore the validity of a strong coupling picture which maps the system onto a Heisenberg model in a random magnetic field. 
C. Huscroft and R.T. Scalettar (U.C. Davis)