Dynamical mass generation in 2+1-dimensional electrodynamics in an   external magnetic field
  The influence of a magnetic field on the mass generation in 2+1 dimensional QED is considered.It is shown that the magnetic field is a catalyst of the generation of a fermion dynamical mass. The mass arises in the system with arbitrary number of fermions, not only with $N\leq 4$, as it is in the system without the magnetic field. The polarization tensor is calculated for a constant magnetic field. 
A.V. Shpagin