[en] The method of dimensional renormalization as applied to quantum electrodynamics is discussed. A general method is given which allows one to compare the various quantities like coupling constants and masses that appear in different renormalization schemes

[en] These few pages are nothing but a brief and incomplete survey of some of the ideas involved in the renormalization group approach

[en] A study is carried out of some of the important developments made in quantum electrodynamics (QED) during this past decade. Basic problems and recent attempts are considered which are expected to be of importance not only for further developments in QED, but also to our further understanding of quantum field theory, in general and of its unique role played in describing the dynamics of elementary particles. (author)

[en] Short communication

[en] The subject of the present work is quantum electrodynamics in the Coulomb gauge whose directional vector is nμ = (1,0,0,0). Primitively divergent graphs of order up to α, the fine-structure constant, are considered. First the known Feynman parts are calculated and used in the renormalization. Then the Coulomb gauge and its problems are outlined. It is seen that the simple renormalization is no longer applicable here as the resual counter terms would be non-polynomial. Therefore other solutions must be sought. (G.Q.)

[en] The authors introduce four fully quantized models of light-matter interactions in optical or microwave cavities. These are the first exactly soluble models in cavity quantum electrodynamics (cavity QED) that provide two transition channels for the flipping of atomic states. In these models a loss-free cavity is assumed to support three or four quantized field modes, which are coupled to a single atom. The atom exchanges photons with the cavity, in either the Raman configuration including both Stokes and anti-Stokes modes, or through two-photon cascade processes. The authors obtain the effective Hamiltonians for these models by adiabatically eliminating an off-resonant intermediate atomic level, and discuss their novel properties in comparison to the existing one-channel Jaynes-Cummings models. They give a detailed description of a method to find exact analytic solutions for the eigenfunctions and eigenvalues for the Hamiltonians of four models. These are also valid when the AC Stark shifts are included. It is shown that the eigenvalues can be expressed in very simple terms, and formulas for normalized eigenvectors are also given, as well as discussions of some of their simple properties. Heisenberg picture equations of motions are derived for several operators with solutions provided in a couple of cases. The dynamics of the systems with both Fock state and coherent state fields are demonstrated and discussed using the model's two key variables, the atomic inversion and the expectation value of photon number. Clear evidences of high efficiency mode-mixing are seen in both the Raman and cascade configurations, and different kinds of collapses and revivals are encountered in the atomic inversions. Effects of several factors like the AC Stark shift and variations in the complex coupling constants are also illustrated

[en] Short communication

No abstract available

No abstract available

[en] A new method is proposed to investigate the internal geometrical structure of an extended particle surrounded by an incomplete virtual dressing field. This method involves analysing the time-dependent virtual field at large distances from the particle, without any direct interaction with the latter. As an example, the pulselike, time-dependent virtual field of an extended QED source is investigated using a model which has a well-known counterpart in meson theory. In the framework of nonrelativistic QED it is shown that, contrary to the case of a point source, the pulse has finite width and height. For the case of a spherically symmetric source, it is explicitly shown that the width and shape of the pulse at distance r from the particle depend on the parameters determining the space structure of the source. It is concluded that the study of the field of half-dressed particles may provide a new method to investigate their internal structure