THE 2-FERMION RELATIVISTIC WAVE-EQUATIONS OF CONSTRAINT THEORY IN THEPAULI-SCHRODINGER FORM

The two-fermion relativistic wave equations of constraint theory are r educed, after expressing the components of the 4x4 matrix wave functio n in terms of one of the 2x2 components, to a single equation of the P auli-Schrodinger type, valid for all sectors of quantum numbers. The p otentials that are present belong to the general classes of scalar, ps eudoscalar, and vector interactions and are calculable in perturbation theory from Feynman diagrams. In the limit when one of the masses bec omes infinite, the equation reduces to the two-component form of the o ne-particle Dirac equation with external static potentials. The Hamilt onian, to order 1/c(2) reproduces most of the known theoretical result s obtained by other methods. The gauge invariance of the wave equation is checked, to that order, in the case of QED. The role of the c.m. e nergy dependence of the relativistic interquark confining potential is emphasized and the structure of the Hamiltonian, to order 1/c(2), cor responding to confining scalar potentials, is displayed. (C) 1994 Amer ican Institute of Physics.