Q operators for the simple quantum relativistic Toda Chain

We investigate the simple quantum relativistic Toda chain. The ultralocal simple Weyl algebra pair is associated with each site of the chain. Weyl’s q is considered to be inside a unit circle. Both independent Baxter operators Q are constructed explicitly as series in local Weyl generators. The operator-valued Wronskian of Q-s is also calculated.     

Gamow Vectors in Exactly Solvable Models

Through two examples: the Friedrichs model and a particular case of central potential scattering, we illustrate the way of constructing Gamow vectors.     

Non-Locality in Electrodynamics

We investigate the applicability of Hegerfeldts arguments on Quantum nonlocality in Quantum Electrodynamics following the work of Prigogine, Pronko, Petrosky, Ordonez and Karpov. We demonstrate the appearance of nonlocal effects at the level of quantum states. We show, however that the expectation values of some observables spread causally. Therefore the measurement of the nonlocality is questionable. We investigate an approach to classical measurement and conclude that the classical measurement cannot detect the acausal effects of the non-locality.     

On Baxter's Q-Operator for the XXX Spin Chain

We discuss the construction of Baxter's Q-operator. The suggested approach leads to the one-parametric family of Q-operators, satisfying wronskian-type relations. Also we have found the generalization of Baxter operators, which defines the nondiagonal part of the monodromy. Received: 5 September 1999 / Accepted: 10 February 2000     

The Long-Distance Asymptotics for the Correlation Function of the Third Spin Components in the XX0 Model with Interaction Through Two Sites

The XX0 chain in the external magnetic field directed along the z axis is discussed. The Hamiltonian describing the exchange interaction between two and four neighboring sites of the chain is constructed. An integral representation for the equal-time temperature correlation function of the third spin components is given. From the long-distance asymptotic of this correlation function, the correlation radius is calculated and its low-temperature behavior is studied. Bibliography: 11 titles.     

String-inspired model for orbital excitations of glueballs

The relativistic string-inspired model of glueballs which contain two valence gluons connected by a straight-line string, is constructed. The model spectrum which consists of five Regge trajectories is compared with the experimental data.     

A kinematical study of Kirchhoff-Rayleigh flow

Summary A method of calculating the separated flow of a viscous fluid is proposed, which allows to split up properly the boundary condition problem from the viscous phenomena. The theory is developed for the flow past a plate and yields wakes of finite extension having an underpressure which depends directly on the amount of vorticity diffusion and dissipation occurring in the fluid. Application of the method to real flows shows good agreement between the calculated and the measured velocity distributions in front of the plate and in the wake.

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Résumé Une méthode de calcul de l'écoulement décollé d'un fluide visqueux est proposée qui permet de séparer clairement le problème aux limites des phénomènes visqueux. La théorie est développée pour l'écoulement autour d'une plaque et donne des sillages de longueur finie ayant une dépression de culot directement dépendante de l'intensité de la diffusion et dissipation de la vorticité se produisant dans le fluide. L'application de la méthode à des écoulements réels montre une bonne concordance entre les répartitions de vitesse calculées et mesurées sur le devant de la plaque et dans le sillage.