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...

In the framework of ‘instantaneous approximations’ to the Bethe–Salpeter formalism for the description of bound states within quantum field theories, depending on the Lorentz structure of the Bethe–Salpeter interaction kernel solutions of the (full) Salpeter equation with some confining interactions may exhibit certain instabilities [1], possibly related to the Klein paradox, signalling the dec...

In this paper, we construct an analytical solution of the one-dimensional spinless Salpeter equation with a Coulomb potential supplemented by a hard core interaction, which keeps the particle in the x positive region. 03.65.Pm,03.65.Ge Typeset using REVTEX Chercheur I.I.S.N. E-mail: [email protected] 1

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-...

We show that there are no dynamic screening corrections to the Salpeter’s enhancement factor in the weak-screening limit. Subject headings: nuclear reactions

An exact form is presented for the axial-vector Bethe-Salpeter equation, which is valid when the quark-gluon vertex is fully dressed. A Ward-Takahashi identity for the Bethe-Salpeter kernel is derived therefrom and solved for a class of dressed quark-gluon-vertex models. The solution provides a symmetry-preserving closed system of gap and vertex equations. The analysis can be extended to the ve...

We show how the invariance under the charge conjugation and CPT symmetry, present in the Bethe-Salpeter equation, is lost in the reduction to certain relativistic three-dimensional equations. This in particular leads to the breakdown of the standard Lorentz structure and renormalization procedures for the resulting single-particle propagators. We formulate the equal-time approximation of the Be...

We analyse the Lorentz structures of weak decay matrix elements between meson states of arbitrary spin. Simplifications arise in the transition amplitudes for a heavy meson decaying into the light one via a Bethe-Salpeter approach which incorporates heavy quark symmetry. Phenomenological consequences of our results on several semileptonic, nonleptonic and flavour changing neutral current-induce...

The most general physical boundary S-matrix for the open XXZ spin chain in the non-critical regime (cosh(η) > 1) is derived starting from the bare Bethe ansazt equations. The boundary S-matrix as expected is expressed in terms of Γq-functions. In the isotropic limit corresponding results for the open XXX chain are also reproduced. e-mail: [email protected]