[en] We consider the problem of modelling of interaction of thin material films with fields of quantum electrodynamics. Taking into account the basic principles of quantum electrodynamics (locality, gauge invariance, renormalizability), we construct a single model for Casimir-like phenomena arising near the film boundary at distances much larger than the Compton wavelength of the electron. In this region, contribution of fluctuations of Dirac fields is not essential and can be neglected. In the model, the film is presented by a singular background field concentrated on a two-dimensional surface and interacting with the quantum electromagnetic field. All the properties of the film material are described by one dimensionless parameter. For two parallel plane films, the Casimir force appears to be non-universal and dependent on the material property. It can be both attractive and repulsive. In the model, we study the scattering of electromagnetic wave on the plane film, interaction of the plane film with a point charge, homogeneously charged plane and straight line current. Here, besides usual results of classical electrodynamics, the model predicts appearance of anomalous electromagnetic phenomena

[en] We present the method of calculation of the radiative decays of composite quark-antiquark QQ-bar systems, with different J ^PC: (QQ-bar)_in →γ(QQ-bar)_out. The method is relativistic invariant; it is based on the double dispersion relation integrals over the masses of the composite mesons; it can be used for high spin particles and provides us with the gauge invariant transition amplitudes. We apply this method to the case when the photon is emitted by a constituent in the intermediate state (additive quark model). We perform the momentum operator expansion of the spin amplitudes for the decay processes. The problem of the nilpotent spin operators is discussed

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[en] The system of the spherical-symmetric vacuum equations of the General Relativity Theory is considered. The general solution to a problem representing two classes of line elements with arbitrary functions g₀₀ and g₂₂ is obtained. The properties of the found solutions are analyzed.

[en] We study quantum electrodynamics coupled to the matter field on a singular background, which we call defect. For defect on an infinite plane we calculated the mean electromagnetic field. Quantum corrections determining the field near the plane are calculated in the leading order of perturbation theory. We analyse the normalization conditions for the parameters of the defect and calculate the photoelectric function of the charged particle from the defect

[en] We study the field theoretical model of a scalar field in the presence of spacial inhomogeneities in the form of one and two finite-width mirrors (material slabs). The interaction of the scalar field with the defect is described with a position-dependent mass term. For a single-layer system we develop a rigorous calculation method and derive explicitly the propagator of the theory, the S-matrix elements and the Casimir self-energy of the slab. Detailed investigation of particular limits of self-energy is presented, and the connection to known cases is discussed. The calculation method is also found applicable to the two-mirror case. With its help we derive the corresponding Casimir energy and analyze it. For particular values of parameters of the model an obtained result recovers the Lifshitz formula. We also propose a procedure to unambiguously obtain the finite Casimir self-energy of a single slab without reference to any renormalization conditions. We hope that our approach can be applied to the calculation of Casimir self-energies in other demanded cases (such as a dielectric ball, etc).

[en] We present calculations of Casimir energy (CE) in a system of quantized electromagnetic (EM) field interacting with an infinite circular cylindrical shell (which we call 'the defect'). Interaction is described in the only QFT-consistent way by Chern-Simon action concentrated on the defect, with a single coupling constant a. For the regularization of UV divergencies of the theory, we use the Pauli-Villars regularization of the free-EM action. The divergencies are extracted as a polynomial in the regularization mass M, and they renormalize the classical part of the surface action. We reveal the dependence of CE on the coupling constant a. Corresponding Casimir force is attractive for all values of a. For a → ∞, we reproduce the known results for CE for perfectly conducting cylindrical shell first obtained by DeRaad and Milton. As a future task for solving existing arguments on observational status of (rigid) self-pressure of a single object, we propose for investigation a system which we call 'Casimir drum'