Unitary Gauge, Stueckelberg Formalism and Gauge Invariant Models for   Effective Lagrangians
  Within the framework of the path-integral formalism we reinvestigate the different methods of removing the unphysical degrees of freedom from spontanously broken gauge theories. These are: construction of the unitary gauge by gauge fixing; \rx -limiting procedure; decoupling of the unphysical fields by point transformations. In the unitary gauge there exists an extra quartic divergent Higgs self-interaction term, which cannot be neglected if perturbative calculations are performed in this gauge. Using the St\"uckelberg formalism this procedure can be reversed, i.~e., a gauge theory can be reconstructed from its unitary gauge. We also discuss the equivalence of effective-Lagrangian theories, containing arbitrary interactions, to (nonlinearly realized) spontanously broken gauge theories and we show how they can be extended to Higgs models. 
Carsten Grosse-Knetter and Reinhart Koegerler (Universitaet Bielefeld,   Fakultaet fuer Physik, D-4800 Bielefeld 1, Germany)