Dirac operators coupled to vector potentials.
Characteristic classes for the index of the Dirac family [unk](A) are computed in terms of differential forms on the orbit space of vector potentials under gauge transformations. They represent obstructions to the existence of a covariant Dirac propagator. The first obstruction is related to a chiral anomaly.
Atiyah
M F
MF
Mathematical Institute, University of Oxford, Oxford, England.
Singer
I M
IM