Spinor-helicity variables for cosmological horizons in de Sitter space

Understand

We consider massless fields of arbitrary spin in de Sitter space.

• We introduce a spinor-helicity formalism, which encodes the field data on a cosmological horizon.
• These variables reduce the free S-matrix in an observer's causal patch, i.e.
• the evolution of free fields from one horizon to another, to a simple Fourier transform.