Soffel, M; Müller, B; Greiner, W, *Stability and decay of the Dirac vacuum in external gauge fields*,
Physics Reports, vol. 85 no. 2
(1982),
pp. 51-122 [doi] .
**Abstract:**

*We consider various gauge fields coupled to the free Dirac equation according to symmetry principles. The gauge fields are treated as classical, unquantized fields. Sufficiently strong time-independent fields may give rise to spontaneous particle creation and to the decay of the symmetric Dirac vacuum into a new ground state with broken symmetry. The vacuum stability of the Dirac field is studied for the cases of external electromagnetic (U(1)), gravitational (Poincaré group including torsion) and Yang-Mills (SU(2)) potentials. © 1982.*