Lipatov's Effective Action Beyond Tree Level
  Computations in Quasi-Multi-Regge kinematics are much simplified using an effective theory pioneered by Lipatov. This high-energy effective theory does not come from an integrating out procedure, and suitable counterterms and regularization have to be provided beyond tree level. In this note we explain this prescription and illustrate it with one- and two-loop examples. 
Jose Daniel Madrigal
hep-ph