DYNAMICAL CHIRAL-SYMMETRY BREAKING BY A MAGNETIC-FIELD IN QED

It is shown that chiral symmetry is spontaneously broken by a constant magnetic field in QED. The dynamical mass of fermions (energy gap in the fermion spectrum) is m(dyn) similar or equal to C root eB exp [-(pi/alpha)(1/2)], where B is the magnetic field, the constant C is of order one, and alpha = e(2)/4 pi is the renormalized coupling constant. Possible applications of this effect are discussed.