Asymptotics of Feynman Diagrams and The Mellin-Barnes Representation
  It is shown that the integral representation of Feynman diagrams in terms of the traditional Feynman parameters, when combined with properties of the Mellin--Barnes representation and the so called {\it converse mapping theorem}, provide a very simple and efficient way to obtain the analytic asymptotic behaviours in both the large and small ratios of mass scales. 
Samuel Friot (CPT, LM-Orsay), David Greynat (CPT), Eduardo de Rafael   (CPT)