Schwinger terms, gerbes, and operator residues

These notes explain recent developments concerning chiral anomalies and hamiltonian quantization, their relation to the theory of gerbes, and extensions of generalized loop algebras using the residue calculus of pseudodifferential operators. The renormalization of the Dirac field, leading to Schwinger terms in equal time commutation relations, is treated in a mathematically rigorous manner. The same renormalization can be used to prove the existence of S-operator in background field problems.Comment: Lectures given at the Banach Center symposium "Differential Geometry and Mathematical Physics", May 15 - 23, 1995. This is an AMS-TEX file. 18 output page

Boundary currents and hamiltonian quantization of fermions in background fields

The current algebra generated by fermions coupled to external gauge potentials and metrics on a manifold with boundary is discussed. It is shown that the previous methods, based on index theory arguments and used in the case without boundaries, carry over to the present problem. The resulting current algebra is the same as obtained from a quantization of bosonic Chern-Simons theories on space-times with nonempty boundaries. This means that also in the fermionic setting the construction is 'holographic', the Schwinger terms reside on the boundary.Comment: 8 pages AmsTex, no figure