Speaker
Description
In this talk, we will review some recent progress in QFT in de Sitter spacetime. We will use the Hilbert-space construction and representation theory of the de Sitter symmetry group, i.e. the Euclidean conformal group, to derive the spectral decomposition of the bulk two-point function and the conformal partial wave expansion of the boundary four-point function. In both cases, unitarity of the bulk theory implies positivity conditions that lead to nontrivial bounds on physical observables. Then, with the goal of bootstrapping the conformal boundary of de Sitter spacetime, I will propose a de Sitter-specific bulk-to-boundary expansion involving a continuous family of boundary operators. Finally, I will derive an inversion formula for the bulk-to-boundary expansion, in which, for a given bulk theory, the boundary operator content is constructed as an integral of the bulk operator multiplied by the bulk-to-boundary propagator. These boundary operators have two-point functions that include contact terms alongside standard CFT two-point functions.