Dynamical Chiral Symmetry Breaking in QED in a Magnetic Field: Toward   Exact Results
  We describe a (first, to the best of our knowledge) essentially soluble example of dynamical symmetry breaking phenomenon in a 3+1 dimensional gauge theory without fundamental scalar fields: QED in a constant magnetic field. 
V. P. Gusynin, V. A. Miransky and I. A. Shovkovy