Quantum Field Theory on Asymptotically Flat Spacetimes and the BMS Group

Explore quantum field theory on asymptotically flat spacetimes and the BMS group in this comprehensive lecture from the Thematic Programme on "Carrollian Physics and Holography." Delve into the construction of Hadamard states for free quantum fields on four-dimensional asymptotically flat spacetimes, focusing on the utilization of BMS asymptotic symmetry group invariance. Examine the rigorous construction of the Unruh state for a massless, conformally coupled, real scalar field on Schwarzschild spacetime, and investigate its application to higher spin, free fields. Conclude by discussing future perspectives of this approach and analyzing existing obstacles in dealing with interacting models.