Generalization of the Extended Lagrangian Formalism on a Field Theory   and Applications
  Formalism of extended Lagrangian represent a systematic procedure to look for the local symmetries of a given Lagrangian action. In this work, the formalism is discussed and applied to a field theory. We describe it in detail for a field theory with first-class constraints present in the Hamiltonian formulation. The method is illustrated on examples of electrodynamics, Yang-Mills field and non-linear sigma model. 
A. A. Deriglazov and B. F. Rizzuti
hep-th math-ph math.MP