It is shown that the motion of an atom is given in a good approximation by Mathisson—Papapetrou equations if we put as a classical angular momentum of the atom the expectation value of the operator of the full angular momentum (including nuclear and electron spins an orbital momentum of the electron).

A conformally invariant zero-mass scalar field with a traceless energy momentum tensor is discussed in static space-time. Exact solutions are obtained for a diagonal metric representing planar, cylindrical and toroidal symmetries in special cases and the calculations are extended to the case of a spherically symmetric spacetime including electromagnetic field. The scalar field may be shown to be formally the same as in Nordtvedt’s general scalar tensor theory for a particular choice of the parameter w as a function of the scalar field \(\psi \).

Static cylindrically symmetric spacetime with an electromagnetic field is discussed in Nordtvedt’s generalized scalar tensor theory of gravitation where the parameter \(\omega \) is a function of the scalar field. Complete solutions are obtained in Dicke’s revised units where the cylindrically symmetric line element can be written in Weyl’s canonical form.

A detailed classification of complex bivectors in space-time is given. The classification is achieved in several ways, with emphasis being laid on the algebraic (Segré type) structure and the geometrical interpretation in complex projective 3-space.

Rigorous relations connecting the behaviour of real and imaginary parts of antisymmetric (symmetric) amplitude at arbitrary energies are obtained. Diverse versions of Pomeranchuk theorem and their generalizations at finite energies follow from these relations.

We have made a semiclassical quantization of solitary wave solutions in the coupled Lund–Regge model. The basic technique of calculation is that of functional integration. The energy levels are deduced corresponding to the periodic boundary conditions. Due to the differential geometric origin of the model, the quantum version may be thought of as a two-dimensional model of quantum gravity.

I discuss the generation of quantum composite operators in two and higher dimensions. In two dimensions the problem is discussed in detail, and the supergravity fields, trivial at the beginning, acquire the status of independent fields, non trivial features being obtained as a consequence. In higher dimensions we are led to non compact symmetry groups when dealing with supergravity. The symmetry SU(\(p,q\)) is discussed; quantization presents several problems. In one case, \(p = q\), it is possible to obtain a prescription leading to finite results, with a quantization procedure breaking the symmetry to SU\((p)\otimes SU(q)\).

Expressions for mean multiplicity of \(g\)-particles in deep inelastic lepton–nuclei interactions are obtained in the framework of multiple scattering theory. These expressions allow one to get information on space-time picture of quark–parton hadronization. \(A\)-dependence of mean multiplicity of \(g\)-particles for (anti-)neutrino-nuclei interactions is obtained using these expressions.

The portion of the Nanopoulos–Srednicki superpotential which yields desired symmetry breaking is generalized to include terms proportional to Tr \(A^4\) and (Tr \(A^2)^2\). We show that the usual symmetry breaking scheme stays unaltered by addition of such terms. In particular we can generate a symmetry breaking SU(5)\(\to \)SU(3)\(\times \)SU(2)\(\times \)U(l), if we introduce realizable restrictions on parameters associated with the terms.

Quantum gluon corrections to the static properties of hadrons are calculated within the framework of quark bag model using noncovariant perturbation theory. As an example baryon magnetic moments are considered. Comparison of quantum and classical approaches is given.

The angular distribution of particles produced in 2115 \(\pi \)-emulsion interactions at 300 GeV has been analysed. The inclusive distribution of shower particles exhibits a pronounced plateau in the central region which extends for about two units of pseudorapidity. Taking advantage of the relation between the number of slow particles emitted from the struck nucleus and the average number of collisions of the projectile inside the target, the dependence of the pseudorapidity distribution on the effective thickness of the target nucleus was investigated.

Separable two-body interactions are used in considering the three-nucleon problem. The nucleon–nucleon potentials are taken to include attraction and repulsion as well as tensor forces. The separable approximation is used in order to investigate the effect of the tensor forces. The separable expansion is introduced in the three-nucleon problem, by which the Faddeev equations are reduced to a well-behaved set of coupled integral equations. Numerical calculations are carried out for the obtained integral equations using potential functions of the Yamaguchi, Gaussian, Takabin, Mongan and Reid forms. The present calculated values of the binding energies of the \(^3\)H and \(^3\)He nuclei are in good agreement with the experimental values. The effect of including the tensor forces in the nucleon–nucleon interactions is found to improve the three-nucleon binding energy by about 4.490% to 8.324%.