Plahte Diagrams for String Scattering Amplitudes

Understand

Plahte identities are monodromy relations between open string scattering amplitudes at tree level derived from the Koba-Nielsen formula.

• We represent these identities by polygons in the complex plane.
• These diagrams make manifest the appearance of sign changes and singularities in the analytic continuation of amplitudes.
• They provide a geometric expression of the KLT relations between closed and open string amplitudes.