Electron Mass Operator in a Strong Magnetic Field and Dynamical Chiral   Symmetry Breaking
  The electron mass operator in a strong magnetic field is calculated. The contribution of higher Landau levels of virtual electrons, along with the ground Landau level, is shown to be essential in the leading log approximation. The effect of the electron dynamical mass generation by a magnetic field is investigated. In a model with N charged fermions, it is shown that some critical number N_{cr} exists for any value of the electromagnetic coupling constant alpha, such that the fermion dynamical mass is generated with a doublet splitting for N < N_{cr}, and the dynamical mass does not arise at all for N > N_{cr}, thus leaving the chiral symmetry unbroken. 
A.V. Kuznetsov, N.V. Mikheev (Yaroslavl State (Demidov) University,   Russia)