Extended Landau Variety and the Singularity Spectrum of Position-Space Feynman Amplitudes

Abstract

It is shown that the singularity spectrum of (generalized) position-space Feynman amplitude Δ_D_(x; λ) is confined to the extended Landau variety (introduced by Kashiwara-Kawai [8], [9] and Kashiwara-Kawai-Stapp [11](0)) associated with the Feynman diagram D(0), which is obtained by replacing all the masses associated with the internal lines of D with zero, at least under the assumption that the diagram D is external.