A relativistic equation is deduced for the bound state of two particles, by assuming a proper boundary condition for the propagation of the negative-energy states. It reduces to the (one-body)Dirac equation in the infinite limit of one of the constituent mass. It also has the symmetries to assure the existence of the anti-bound-state with the same mass. The interaction kernel(pseudo-potential) ...

Perturbative QeD may be subdivided into separately gauge-invariant sectors according to the projection of non-abelian color weights onto linearly independent basis elements. We exploit the general Lie group structure of the theory to give an algorithm for finding these gauge-invariant sets and present several examples of its use. The planar sector and the systematks of the non-planar correction...

A system of two Korteweg-de Vries equations coupled by small linear and nonlinear terms, which is a model of a resonant interaction between two internal gravity-wave modes in a shallow stratified liquid, is considered. The present paper is a continuation of a preceding one, where only the linear coupling was dealt with. Various dynamical processes involving one-mode solitons are investigated. I...

We derive the (matrix-valued) Feynman rules of mass perturbation theory of the massive Schwinger model for non-zero vacuum angle θ. Further, we discuss the properties of the three-boson bound state and compute – by a partial resummation of the mass perturbation series – its mass and its partial decay widths.

Operating just once the naive Foldy-Wouthuysen-Tani transformation on the Schrödinger equation for Qq̄ bound states described by a hamiltonian, we systematically develop a perturbation theory in 1/mQ which enables one to solve the Schrödinger equation to obtain masses and wave functions of the bound states in any order of 1/mQ. It is shown that positive energy projection with respect to the heav...

In this series of lectures, I shall begin with the current investigations on phenomenology of hadron dynamics to demonstrate the importance of solving hadronic bound states within the framework of light-front (LF) QCD. Then, I will describe the basic procedure how to formulate the canonical theory of LFQCD, including lightfront quantization of QCD, light-front gauge singularity, and light-front...

By a closer inspection of the massive Schwinger model within mass perturbation theory we find that, in addition to the n-boson bound states, a further type of hybrid bound states has to be included into the model. Further we explicitly compute the decay widths of the three-boson bound state and of the lightest hybrid bound state. )permanent address: Inst. f. theoret. Physik d. Uni Wien Boltzman...

We develop a perturbation theory that describes bound states of solitons localized in a confined area. External forces and influence of inhomogeneities are taken into account as perturbations to exact solutions of the sine-Gordon equation. We have investigated two special cases of fluxon trapped by a microresistor and decay of a breather under dissipation. Also, we have carried out numerical si...

In this paper, we develop bounds on the distribution function of the empirical mean for general ergodic Markov processes having a spectral gap. Our approach is based on the perturbation theory for linear operators, following the technique introduced by Gillman. Mathematics Subject Classification. 60F10. Received February 19, 2001. Revised September 21 and October 1, 2001.

• We give a 1.5-approximation for half-integral weighted MSCSS. Our matches known integrality gap lower bound. 2 − f approximation if LP values are bounded below by . In the minimum strongly connected spanning subgraph ( WMSCSS ) problem we must purchase minimum-cost of digraph. show that linear program (LP) solutions can be efficiently rounded to integral at multiplicative 1.5 cost. This round...