Concatenating Variational Principles and the Kinetic Stress-Energy-Momentum Tensor

Castrillon Lopez, M., M. J. Gotay and J. E. Marsden

Variations, Geometry and Physics, (2008), 117-128

Abstract:

We show how to “concatenate” variational principles over different bases into one over a single base, thereby providing a unified Lagrangian treatment of interacting systems. As an example we study a Klein–Gordon field interacting with a mesically charged particle. We employ our method to give a novel group-theoretic derivation of the kinetic stress-energy-momentum tensor density corresponding to the particle.