Pomeranchuk Exchange and Low-Energy Theorems in Compton Scattering

Abstract

The method, introduced in a previous work, of deriving the kinematical properties of zero-mass bosons from the limit of a theory with massive particles is here applied to the problem of Compton scattering. It is shown that the same mechanism that eliminates the factor of ${\ensuremath{\alpha}}_{\ensuremath{\pi}}(t)$ from the nonsense amplitude in pion photoproduction processes and allows the pion pole to occur in such amplitudes also removes the nonsense factor of ${\ensuremath{\alpha}}_{P}\ensuremath{-}1$ from the residue of the Pomeranchuk trajectory in Compton scattering. This allows the Pomeranchuk exchange to contribute to the photoabsorption total cross section. The connection of this result with the vector-dominance model is discussed. A short derivation of the low-energy theorems for Compton scattering using this limiting procedure is also given.