may consider a model with only one extra dimension (a type of Kaluza–Klein model) and compactify down to a four-dimensional theory. The resulting Lagrangian will contain massive vector gauge bosons that acquire masses through the Stueckelberg mechanism. See also Higgs mechanism#Affine Higgs mechanism References The edited PDF files of the physics course of Professor Stueckelberg, openly accessible, with commentary and complete biographical documents. Review:Stueckelberg Extension of the Standard Model and the MSSM Boris Kors, Pran Nath: , , Daniel Feldman, Zuowei Liu, Pran Nath: , Gauge theories Physics beyond the Standard Model Symmetry Theoretical physics