How to determine the branch points of correlation functions in Euclidean space

Understand

Two-point correlators represented by either perturbative or non-perturbative integral equations in Euclidean space are considered.

• In general, it is difficult to determine the analytic structure of arbitrary correlators analytically.
• When relying on numerical methods to evaluate the analytic structure, exact predictions of, e.g., branch point locations (i.e., the multi-particle threshold) provide a useful check.
• These branch point locations can be derived by Cutkosky's cut rules.