The main purpose of these lectures is to give an introduction to the theory of invariant linear
wave equations and their associated external field problems. Certain special equations …

On a Relativistically Invariant Formulation. 199 which the ψ-vector depends no longer on C,
but the field quantities, on the other hand, depend on C, not only on t. Also in our …

A general procedure is given for constructing infinitely many systems of wave equations and
subsidiary conditions for a particle of given spin and nonzero mass. The subsidiary …

In the presence of an electrostatic field (but not for a static world scalar or magnetostatic
field) the stationary solutions of the quadratic relativistic wave equation for scalar particles …

Rarita and Schwinger,'and Bargmann and Wig-ner, for example, are suitable only for the
description of free particles. The existence of subsidiary conditions which are consistent only …

According to the general program proposed in the first paper, Koba, Tati and one of the
present authors have given in the second paper a perfectly relativistic formulation of the …

The possibility of formulating covariant field equations for particles of arbitrary spin and
nonzero mass is considered. Using only the transformation properties of the single-particle …

The first term HO in (5.13) does not contain the electromagnetic potential and has the same
form as (5.6). This part of HVM represents thus the Hamiltonian density of the free meson …

The present chapter develops the external field problem in a form which covers the
possibility that the field is quasi-local, a possibility which we know must be reckoned with in …

A wave equation is given which, in the force-free case, describes a particle of unique spin
and mass and which remains consistent when interactions are included. The equation is …