Chiral Symmetry Breaking and Point-Splitting Procedure in Light-Cone   Quantized QED in a Magnetic Field
  The summation of all rainbow diagrams in QED in a strong magnetic field leads to a dynamical electron mass on the light-cone. Further contributions to this summation however can cause problems with light-cone singularities. It is shown that these problems are generally avoided by applying the point-splitting regularization to every diagram. The possibility of implementing this procedure into the Lagrangian of the theory is discussed. 
D. Steinbacher (Erlangen-Nuremberg U., Theorie III)