Cutting Rule for Cosmological Collider Signals: A Bulk Evolution
  Perspective
  We show that the evolution of interacting massive particles in the de Sitter
bulk can be understood at leading order as a series of resonant decay and
production events. From this perspective, we classify the cosmological collider
signals into local and nonlocal categories with drastically different physical
origins. This further allows us to derive a cutting rule for efficiently
extracting these cosmological collider signals in an analytical fashion. Our
cutting rule is a practical way for extracting cosmological collider signals in
model building, and can be readily implemented as symbolic computational
packages in the future.
