Relativistic-particle interactions—A third world view

Abstract

A new form for describing interacting relativistic classical particles with invariant world-lines is presented. In contrast to the use of independent particle variables or of «centre of mass» and relative co-ordinates previously considered in the literature, we introduce a Lorentz matrix and an associated conjugate four-dimensional angular momentum as collective variables; these are supplemented with a suitable number of internal variables. The methods of constrained Hamiltonian dynamics are used to ensure that the number of independent degrees of freedom corresponds precisely to that for a system of a given number of particles. Independent particle variables can be defined in the formalism, and interactions included. The eleventh-generator form for relativistic Hamiltonian dynamics is essential to make relativistic invariance, invariant world-lines and interaction compatible with one another.