The Feynman problem for the Klein-Gordon equation
arXiv:2003.14404
Abstract
We report on the well-posedness of the Feynman problem for the Klein-Gordon equation on asymptotically Minkowski spacetimes. The main result is the invertibility of the Klein-Gordon operator with Feynman conditions at infinite times. Furthermore, the inverse is shown to coincide with the Duistermaat-Hörmander Feynman parametrix modulo smoothing terms.
short review article, to appear in "Séminaire Laurent Schwartz - EDP et applications" proceedings