We study an approach to the relativistic two-body problem that represents a considerable
improvement of the Bethe-Salpeter equation. The main advantages are the improved …

We propose a new relativistic two-body formalism which reduces to a nonrelativistic
Schrödinger theory for a single effective particle. The formalism is equal in rigor to that of …

Relativistic atomic theory is based on the Dirac-Breit equation which in turn is derived from
the standard single-time QED. This derivation is largely nonperturbative due to the use of …

A new formalism for the description of the two-body system and well suited to the bound-
state problem is developed within the context of quantum electrodynamics. The resulting two …

We classify the various 3D reductions of the Bethe-Salpeter equation for two fermions,
according to the constraint chosen. We show that, for a given choice of the constraint, the …

We examine novel formulations of the two-body bound state problem in quantum field
theory. While equal in rigor, these have several calcula tions! advantages over the traditional …

We perform a 3D reduction of the two-fermion homogeneous Bethe–Salpeter equation, by
series expansion around a positive-energy instantaneous approximation of the Bethe …

The logarithmic part of the Lamb shift, the contribution of the relative order α 3 log (1/α) to the
atomic state energy, is related to the usual infrared divergence. This fact allows one to …

Abstract The Bethe-Salpeter equation is cast into a form in which the relationship between
the relativistic quantum-mechanical two-body equation and the Bethe-Salpeter equation is …

We construct relativistic wave equations describing the dynamics of two interacting particle
systems involving spin-0 bosons and/or spin-(1/2) fermions. The method consists in …