The application of unitarity and dispersion relations to Delbruck scattering: and a new approach to pion-nucleon scattering

The conclusion of this work is really very small. It is that the five dimensional integral for the imaginary part of the Delbruck scattering amplitude allows two further integrations to be carried out analytically, before it is absolutely necessary to resort to machine computation. Whether it would be quicker to carry out the work fully, i.e. obtain a three dimensional integral representation for the imaginary part, and then integrate numerically, or to find another computing programme, which allows one to integrate the five dimensional integral at higher energies is another question