Seminarium KMMF "Teoria Dwoistości"

We give a new construction based on pseudo-differential calculus ofquasi-free Hadamard states for Klein-Gordon equations on a class ofspace-times whose metric is well-behaved at spatial infinity. Inparticular we construct all pure Hadamard states and study theircovariance under symplectic transformations. Using our results we givea new construction of Hadamard states on arbitrary globally hyperbolicspace-times. (Joint work with Michal Wrochna).