abstract

It is shown that for a Minkowski background the Nonsymmetric Theory, unlike General Relativity, collapses into a description of the classical electromagnetism.

abstract

Spherically symmetric solutions of Einstein equations in a one-parameter class of coordinates which generalize the harmonic coordinates are obtained. It is shown that in these coordinates the time component of the source tensor of the Schwarzschild field is proportional to the Dirac delta function while the remaining components vanish. It is shown also that the gravitational momentum of the Schwarzschild field is equal to the sum of the field momentum and the inertial momentum in two coordinate systems only. This equality may be treated as sort of a “natural” condition which selects privileged coordinate system.

abstract

Isotropic hypersurfaces admitting inner groups of motions are classified. Normal forms for the inner metric are given, and its geometric properties are characterized by means of differential invariants. The problem of embedding a given null hypersurface into empty spacetime is studied locally.

abstract

No-Interaction Theorems in Relativistic Action-at-a-Distance Mechanics are reviewed. The most suggestive proofs are quoted and some of them are simplified. Physical requirements which \(N\)-Particle Predictive Relativistic Dynamics should satisfy are formulated and the existing examples are discussed. Some methods of constructing examples of Predictive Relativistic Dynamics are proposed.

abstract

The \(\pi ^+\) kinetic energy spectrum in the K\(^+ \to \pi ^+\pi ^0\pi ^0\) decay is analysed between 1 and 45 MeV. Three forms of the decay matrix element are fitted. Existence of possible \(\pi ^0\pi ^0\) interaction is discussed.

abstract

We study the cross sections for gluon jet production in deep inelastic leptoproduction as predicted by QCD perturbation theory. Using a nonperturbative chain decay model for parton jet fragmentation, we study the cross section for two-jet (quark and spectator) and three-jet (quark, gluon and spectator) production. The cross section is studied in terms of the thrust variable, transverse momentum and transverse momentum sum of hadrons relative to the momentum transfer direction, and in terms of the variable in the Breit frame. We find it possible to detect gluon jet effects for lepton energies starting with about 200 6eV and at as large as possible values of Q2 and W2. The transverse momentum sum is found to be the most useful variable for identifying gluon jets.

abstract

Spin properties of a dyonium system formed from spinless dyons are considered. It is shown that this composed particle can be treated as a fermion if one takes into account the additional degrees of freedom connected with the Dirac string.

abstract

Total cross sections for (n,\(\alpha \)) reactions on the target nuclei \(^{31}\)P, \(^{51}\)V, \(^{55}\)Mn, \(^{59}\)Co, \(^{75}\)As and \(^{139}\)La have been measured in the neutron energy range 13–18 MeV. The results are discussed in terms of the compound nucleus and the precompound emission models, together with some estimate of the direct mechanism component.

abstract

Heavy ion elastic scattering calculations lead to numerical difficulties in the regions of energies and angles where the cross sections are small. Two different approximate methods have been investigated in the case of \(^{20}\)Ne + \(^{24}\)Mg scattering at \(E_{\rm LAB} = 100\) MeV. The emerging errors of calculations are traced in detail. It is shown, that the optical model calculations are critically sensitive to some details which are arbitrarily assumed in commonly used approximate methods. The obtained results allow to perform similar calculations with controlled accuracy and some ambiguities of optical model potentials can be removed.