Table of contents

A large number of recent articles are devoted to the theory of Van-der-Waals forces between macroscopic bodies, and to a number of related questions. Attention is being paid both to the solution of various concrete problems and to the development of a general theory. The latter is necessitated by the fact that the Van-der-Waals theory of forces between bodies is known to be quite cumbersome. Through certain efforts, the theory expounded in this review has been simplified in certain respects, and was also generalized. The review describes, first, a "simple" theory of Van-der-Waals forces (Chap. 2), which in our opinion is particularly clear and technically simple without adversely affecting the accuracy of the calculations. Second, we develop and describe a rather common and seemingly sufficiently lucid approach, which permits calculation of the contribution of the long-wave equilibrium electromagnetic field and the thermodynamic characteristics of condensed bodies (Chap. 3). Third, results are presented of a number of concrete calculations for Van-der-Waals forces between bodies (Chap. 4).

A review is given of the current status of the polarization magneto-optics of crystals with paramagnetic impurity ions. Methods for measuring the magnetic circular anisotropy are discussed and a review is given of the results obtained in recent years by traditional magneto-optic investigations (including the magnetooptic activity in the absorption spectra of intrinsic and impurity defects in crystals, magnetic circular polarization of the luminescence, and anisotropy of the magneto-optic activity in cubic crystals). Attention is concentrated on new methods in polarization magneto-optics, which include investigations of the interaction of the spin system with the crystal lattice, particularly the spin-lattice relaxation and spin memory effects, experiments on radio-optic double resonance, investigations of the optical spin relaxation, nonlinear magneto-optic effects, etc.

This article review the current state of the quasisteady-state theory of the high frequency electrical properties of sources (probe antennas) in a plasma in which one can neglect the collisions of the charged particles. We discuss the structure of the potential and of the electric field, the impedance and the noise; the effect on these characteristics of a d.c. magnetic field, of excitation of plasma oscillations, thermal and directional movement of particles (passage effects), of deposition of particles on the surface of sources, etc. When plasma oscillations are excited, we show that the electric field usually or generally does not decline with distance from the source, or declines considerably more slowly than in a vacuum. We demonstrate that the fundamental characteristics of "large" sources (of dimensions large in comparison with the spatial-dispersion parameter) can be determined in the "cold" plasma approximation, in which the equation for the potential is generally an equation of mixed type, while the solutions of physical interest are complex. For "small" sources, the principal effect studied is the passage of electrons in the inhomogeneous a.c. field of the source. Expressions are given for the impedance and noise of sources with account taken of passage effects. We note that finite particles should exert in a number of cases a substantial effect on the characteristics of "small" sources.

This review is concerned with the various theoretical approaches to the problem of e⁺e^– annihilation into hadrons in the light of the new experimental data obtained in 1973-4. Discussions are given of the behavior of the total cross section for e⁺e^– annihilation into hadrons, the form of the inclusive spectra, the dependence of the particle form factors in the timelike region on the square of the momentum transfer, and the effect of the process of e⁺e^– annihilation into hadrons on scattering by positrons and on the process e⁺e^–→μ⁺μ^–. Other topics considered include the relation between inclusive annihilation and electroproduction, as well as a number of theoretical models: the parton model, the statistical model, etc.

A review is given of experimental studies of the beta decay of the free neutron carried out up to the present time. Data are given on the beta spectrum, half-life, and all four possible angular correlations in the decay of polarized neutrons. The features of the experimental apparatus are considered, and the main problems in the experimental technique of the corresponding measurements are discussed. The shape of the beta spectrum does not reveal any important deviations from a Fermi spectrum for allowed transitions. There are two values for the half-life, which do not agree with each other: T_1/2 = 11.7±0.3 min (from the work of P. E. Spivak et al. in 1959) and T_1/2 = 10.6±0.16 min (from the work of C. Christensen et al. in 1971). No angular correlation has been observed between the neutron spin and the decay plane (violating T parity). The corresponding triple correlation constant is given by the latest data as D = (-1.1±1.7)×10^-3 (Grenoble, 1974) and D = (-2.7±3.3)×10^-3 (Moscow, 1974). Comparison of all the experimental data with each other shows that the weighted mean value of the neutrino-electron, neutron spin-electron, and neutron spin-neutrino angular-correlation constants are in good agreement with each other, and also with the result of the last measurement of the decay constant, within the framework of the V-A theory of weak interaction, and lead to a value of the fundamental ratio G_A/G_V = 1.263 ±0.016. However, as shown in the review, the accuracy of the measurements achieved up to the present time is completely inadequate to exclude very substatial contributions of scalar (up to 30-40%) or tensor (up to 15%) terms in the Hamiltonian of the weak interaction.