XXVI Workshop on Geometric Methods in Physics 1-7.07.2007

Gerald Goldin

Lagrangian and Non-Lagrangian Approaches to Generalized Gauge Theories (tentative)

Motivated by the desire to construct generalized Maxwell and Yang-Mills field theories with nontrivial Galilean limits (taking c to infinity), one may base an approach on the introduction of nonlinear constitutive equations, which may or may not derive from a Lagrangian functional (joint work with V. Shtelen). The result turns out to be relevant to a different limit, that of the tensionless string in Born-Infeld theory (joint work with N. Mavromatos and R. Szabo). I shall review some of these results, discuss the implications of Lagrangian and non-Lagrangian approaches, and consider some further generalizations that Shtelen and I are presently exploring (with S. Duplij).