How To Classify 3-Body Forces -- And Why
  For systems with only short-range forces and shallow 2-body bound states, the typical strength of any 3-body force in all partial-waves, including external currents, is systematically estimated by renormalisation-group arguments in the Effective Field Theory of Point-Like Interactions. The underlying principle and some consequences in particular in Nuclear Physics are discussed. 
Harald W. Griesshammer (TU Muenchen and University of   Erlangen-Nuernberg)