Paramagnetism, zero modes, and mass singularities in QED in 1+1, 2+1, and 3+1 dimensions

The interplay of paramagnetism, zero modes of the Dirac operator, and fermionic mass singularities on the fermionic determinants in quantum electrodynamics in two, three, and four dimensions is discussed. {copyright} {ital 1997} {ital The American Physical Society}