Nonphysical Region Singularities of the S Matrix
Peter A. Goddard · Journal of Mathematical Physics · 1970
The work of a previous paper, which examined the relationship between the assumption of Cutkosky-type discontinuity formulas to the positive-α condition for the singularity of anomalous thresholds, is extended using more powerful methods. The method is first described in general terms. It is then justified using homological techniques, and specific expressions are calculated for distortion terms. Finally, some specific cases are considered and more elaboration versions of the cancellation processes previously found are shown to occur.