Conditional gauge theorem for non-local Feynman-Kac transforms

Feynman-Kac transforms driven by discontinuous additive functionals are studied in this paper for a large class of Markov processes. General gauge and conditional gauge theorems are established for such transforms. Furthermore, the L^2infinitesimal generator of the Schr?dinger semigroup given by a non-local Feynman-Kac transform is determined in terms of its associated bilinear form.