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We study QFT systems with spatial 2d defects describing thin material films. We describe the defects introducing into the action of a model a potential term with singular background supported on the defect. Such potentials generalize boundary conditions imposed on the quantum fields. We show that satisfying all basic field-theoretical principles - locality, renormalizability, gauge and Lorenz invariance (if applicable), - defines uniquely the form of potential for given types of fields (scalar, spinor, EM). Within the Path Integral approach we calculate exactly the propagators and functional determinants for QED models with augmented action. The parameters of potential of the fermion defect characterize charge density, 3d spacial current and other classical (macroscopical) properties of the defect. The photon potential is unavoidably of Chern-Simon type and its single dimensionless constant characterizes the parity breaking of the system. The behavior of such systems is similar to a magnetoelectric ones. Being renormalizable these models give opportunity to investigate in details behavior of the divergences in Casimir Energy and any other observable. For fermion field interacting with an infinite plane we present calculation of quantum corrections to classical Electromagnetic (EM) field of the plane. The cut-off regularization of the mean EM field gives rise to renormalization of classical EM current of the plane. For EM quantum fields in presence of two planes, or a sphere or an infinite circular cylinder we present the Casimir Energy calculations for which we use the Pauli-Willars regularization procedure. The divergences are extracted as a polynomial in the regularization mass parameter and then embodied into the counter terms. by Fialkovsky I.V., Markov V.N. and PisĒmak Yu.M. |
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