Florian Hanisch
The spectral shift function is an object from scattering theory. It was invented to describe/compute traces of certain operators and generalizes the notion of spectral flow. It is moreover closely related to the Witten index of operators which itself generalizes the Fredholm index, also to certain non-Fredholm situations. We will briefly introduce both concepts, sketch their relation and if time allows, give some vague ideas why this could be interesting in the Lorentzian case.
