A GAUGE-INVARIANT HAMILTONIAN DESCRIPTION OF THE MOTION OF CHARGED TEST PARTICLES

New, gauge-independent, second-order Lagrangian for the motion of clas sical, charged test particles is used to derive the corresponding Hami ltonian formulation. For this purpose a (relatively little known) Hami ltonian description of theories derived from second-order Lagrangians is presented. Unlike in the standard approach, the canonical momenta a rising here are explicitly gauge-invariant and have a clear physical i nterpretation, The reduced symplectic form obtained this way is (almos t) equivalent to Souriau's form. This approach illustrates a new metho d of deriving equations of motion from field equations, (C) 1998 Publi shed by Elsevier Science B.V.