Partial fraction decomposition for flat-space cosmological wavefunctions

Prove the partial fraction decomposition for the flat space wave function ψ_flat associated with an arbitrary Feynman graph, as formulated in Fevola–Pimentel–Sattelberger–Westerdijk (Conjecture 3.5).

Background

Cosmological correlators and wavefunctions often admit representations amenable to algebraic analysis (GKZ systems, D-modules). A conjectured partial fraction decomposition for ψ_flat would yield structural simplifications and pave the way for efficient computation and analytic continuation. Validating this decomposition across all Feynman graphs would significantly impact the algebraic approach to cosmological integrals.