Gribov's Reggeon-Graph Technique

Gribov has recently extracted the high-energy behavior of some Feynman graphs using a parametrization due to Sudakov. His results can be systematically written in terms of Reggeon graphs. He postulates that the asymptotic form of higher-order graphs can also be written this way. We discuss some of Gribov's results and show that they depend on (i) the formation of pinches as $s\to \infty$, (ii) a certain restriction on the region of integration. From this discussion we extend Gribov's results to graphs of arbitrarily high order and confirm the graph technique.