Extended calculations of the deuteron's static properties, based on the numerical solution of the Bethe-Salpeter equation, are presented. A formalism is developed, which provides a comparative analysis of the covariant amplitudes in various representations and nonrelativistic wave functions. The magnetic and quadrupole moments of the deuteron are calculated in the Bethe-Salpeter formalism and t...

For two bound-state equations derived as simplified forms of the Bethe–Salpeter equation with confining interaction, stability of all solutions is rigorously shown. 1 Motivation: Instabilities of Klein-Paradox Type The Salpeter equation is a frequently applied three-dimensional reduction of the Bethe–Salpeter formalism describing bound states within quantum field theory, derived by assuming all...

The instantaneous Bethe–Salpeter equation, derived from the general Bethe–Salpeter formalism by assuming that the involved interaction kernel is instantaneous, represents the most promising framework for the description of hadrons as bound states of quarks from first quantum-field-theoretic principles, that is, quantum chromodynamics. Here, by extending a previous analysis confined to the case ...

The behavior of the two-particle Green's function in QED is analyzed in the limit when one of the particles becomes infinitely massive. It is found that the dependences of the Green's function on the relative times of the ingoing and outgoing particles factorize and that the bound state spectrum is the same as that of the Dirac equation with the static potential created by the heavy particle. T...

The 'Salpeter Equation' which has long been known as the 3D version of the 4D Bethe-Salpeter Equation under the Instantaneous Approximation, has a well-defined rationale that stems from the half-century old Markov-Yukawa Transversality Principle (M Y T P) which not only effects an exact 3D reduction from the original (4D) BS form, but also provides an equally exact reconstruction of the 4D BS a...

Recent developments of the covariant Bethe–Salpeter (BS) approach with the use of the separable interaction for the deuteron are reviewed. It is shown that the BS formalism allows a covariant description of various electromagnetic reactions like the lepton-deuteron scattering, deuteron electro-disintegration, deep inelastic scattering (DIS) of leptons on light nuclei. The procedure of the const...

We compute by means of the Bethe Ansatz the boundary S matrix for the open anisotropic spin-12 chain with diagonal boundary magnetic fields in the noncritical regime (∆ > 1). Our result, which is formulated in terms of q-gamma functions, agrees with the vertex-operator result of Jimbo et al.

We investigate the relation between the rank I separable potential for the covariant Bethe-Salpeter equation and the one-boson-exchange potential. Parameters of the two potentials are related in the long wave length limit. It turns out that it is difficult to reproduce the phase-shifts calculated from a single term of the one-boson-exchange potential , separately by the rank I separable potenti...

The electromagnetic E1 and M1 transitions in heavy quarkonia (c¯ c , b ¯ b , c ¯ b) and the magnetic moment of the B ± c are calculated within the framework of the covariant Blankenbecler-Sugar (BSLT) equation. The aim of this paper is to study the effects of two-quark exchange current operators which involve the Q ¯ Q interaction, that arise in the BSLT (or Schrödinger) reduction of the Bethe-...