Wavefunctionals/S-matrix techniques in de Sitter

Understand

Flat-space physics is highly constrained by basic principles such as Lorentz invariance, locality, unitarity and causality.

• This is neatly seen in the structure of scattering amplitudes.
• For processes occurring in an expanding background we do not have the same level of understanding, not even in the case of de Sitter space.
• In this talk I provide a brief account of some of the recent efforts which aim to fill this gap.