
%0 Journal Article
%A Cunningham, J 
%T Complex Singularities in Production Amplitudes
%J Australian Journal of Physics
%D 1964/06/01
%V 17
%N 2
%P 161-164
%K 
%R https://doi.org/10.1071/PH640161
%U https://www.publish.csiro.au/paper/PH640161 
%X Complex singularities in the ",+N --? "'+ ",+N amplitude corresponding to vertex contractions of the single-loop Feynman diagram exist on the physical sheet of the amplitude irrespective of whether the theory is formulated in terms of timeordered or retarded products_ 
