DYNAMICAL FLAVOR SYMMETRY-BREAKING BY A MAGNETIC-FIELD IN 2+1 DIMENSIONS

It is shown that in 2 + 1 dimensions a constant magnetic held is a str ong catalyst of dynamical flavor symmetry breaking, leading to generat ing a fermion dynamical mass even at the weakest attractive interactio n between fermions. The essence of this effect is that in a magnetic f ield, in 2 + 1 dimensions, the dynamics of fermion pairing is essentia lly one dimensional. The effect is illustrated in the Nambu-Jona-Lasin io model in a magnetic field. The low-energy effective action in this model is derived and the thermodynamic properties of the model are con sidered. The relevance of this effect for planar condensed matter syst ems and for (3 + 1)-dimensional theories at high temperature is pointe d out.