Tree-Loop Duality Relation beyond simple poles
  We develop the Tree-Loop Duality Relation for two- and three-loop integrals with multiple identical propagators (multiple poles). This is the extension of the Duality Relation for single poles and multiloop integrals derived in previous publications. We prove a generalization of the formula for single poles to multiple poles and we develop a strategy for dealing with higher-order pole integrals by reducing them to single pole integrals using Integration By Parts. 
Isabella Bierenbaum, Sebastian Buchta, Petros Draggiotis, Ioannis   Malamos, German Rodrigo
hep-ph hep-th