abstract

Field equations corresponding to plane-symmetric interacting zero-mass scalar fields and a perfect fluid distribution have been solved exactly for the following physically important cases: (a) Disordered distribution of radiation (\(D=3p\)); (b) Zeldovich fluid distribution (\(D=p\)); (c) Perfect fluid distribution (\(D\not =p\)): (d) Matter distribution in internebular space (\(D=3p/2\)). For case (a) it has been observed that the only possible distribution that can exist is an unbounded plane-symmetric, asymptotically tending to plane-symmetric vacuum solution. Various physical behaviour that the solutions represent have been studied paying special attention to the pressure, density and energy-content per unit volume.

abstract

In this paper we consider the so-called Maxwellian tensors for the curvature and for the torsion of the space-time and the total superenergy and superspin tensors in the theory of gravitation with quadratic Lagrangian \(L_g=\varrho ^{{\mit \Omega } i.}_{.j}\wedge \eta ^{.j}_{i.}+\bar a {\mit \Omega }^{i}_{.j} \wedge \ast {\mit \Omega }^j_{.i}+\alpha {\mit \Theta }^i \wedge \ast {\mit \Theta }_{i.}\)

abstract

The algebraic study of a (trace-free) symmetric tensor as a quadric surface in complex projective 3-space, leading to a quartic curve on the fundamental quadric surface determined by the metric tensor, is reconsidered. This approach, first given by Penrose and later by Cormack and Hall is simplified and more details are given. This enables a simple comparison with more conventional classification schemes. The geometrical aspects and interpretations are stressed throughout.

abstract

A method of constructing examples of Predictive Relativistic Dynamics on the basis of Lagrange formalism is presented. Kerner’s one dimensional example is obtained.

abstract

The rigorous lower bound for the elastic-to-total cross-section ratio is derived at finite energies in analytical form. The obtained bound allows one to make numerical estimates of total cross-section which are sufficiently close to corresponding experimental data.

abstract

Tests of Quantum Electrodynamics by the reactions \(e^+e^- \to e^+e^-\), \(\mu ^+\mu ^-\), \(\tau ^+\tau ^-\) and \(\gamma \gamma \) at center of mass energies of up to 31 GeV are described. The measurements were done at the \(e^+e^-\) storage ring PETRA at DESY in Hamburg mainly with the PLUTO detector. Results on QED cutoff parameters \({\mit \Lambda }\), and an electroweak effects are given.

abstract

In the framework of multiple scattering theory the expressions are obtained for the mean number of inelastic collisions of leading hadron and the mean multiplicity of shower particles \(\langle n_{\rm S} \rangle _{\rm pA}\) in proton–nucleus interactions; change of type of the leading hadron (transfer of leading property from a nucleon to a pion) is taken into account. The comparison of calculations with experimental data shows that the multiplicity excess of shower particles in nucleon–nucleus collisions as compared with the nucleon–nucleon ones cannot be entirely due to multiple inelastic interactions of the incident nucleon but is apparently also due to inelastic interactions of secondary particles, mainly the leading pion collisions.