Majorana Neutrinos with Displaced Vertices and Implementation into Sherpa

The inclusion of the Seesaw model type I into Sherpa using UFO is explained. Installation is validated by comparing simulated partial and total decay widths for Majorana neutrinos to analytic theoretical predictions. Vertex displacements are implemented for high energy elementary particle decays the following way. A pseudo-random rest frame lifetime is generated according to the physical distribution. It is boosted into the lab oratory system and using the particle's momentum the decay position is estimated.