abstract

A method is given by which we can generate asymptotically flat axially symmetric electrovac metrics from solutions representing empty space gravitational fields. The method allows us to generate an infinite chain of solutions of source free Einstein–Maxwell equations. Several new electrovac solutions are obtained from the gravitational fields found by Schwarzschild and Zipoy. A method is also given for generating an analogous stationary solution of source-free Einstein equations.

abstract

A quantized scalar field in an external time-dependent gravitational field is considered. The complete Lagrangian contains terms quadratic in the curvature. These terms are connected with the removing of infinities appearing in the vacuum expectation value of the energy-momentum tensor and characterize a back reaction effect. The methods of the gauge fields theory are used. It is shown that in the isotropic time-dependent gravitational field the back reaction effect leads to the absence of solutions with physical singularities. It is noted that the particle creation is small in the considered case.

abstract

Nonlinear scalar interactions of the form \(N\sum \limits ^{\infty }_{i=1}\frac {c_i}{i!}({\mit \Phi }^2/N)^i\) are considered in the large \(N\) limit. The renormalization of the generating functional for Green’s functions in three dimensions is performed up to the next to leading order. The induced derivative couplings are absent to this order. The generality of the approach allows one to study all nonlinear \(O(N)\)-symmetric scalar interactions, provided they are expandable in a Taylor series in \({\mit \Phi }^2/N\).

abstract

De Groot’s method of calculating the longitudinal phase-space integrals is generalized to include leading particles. The generalization simplifies practical calculations of all quantities predicted by the uncorrelated jet model with leading particles.

abstract

The set \(P\) of particles is supposed to be partly ordered by an invariant ordering relation which makes the set \(P\) a complemented distributive lattice. As a consequence, hadrons may be regarded simultaneously as bound states of heavy unstable constituents or as particles composed of light stable quasifree constituents, the two basic sets of constituents being in a bootstrap-type connection. Some phenomenological implications (average quark mass, the high energy behaviour of \(R(\sigma (e^+e^- \to \) hadrons)\(/\sigma (e^+e^- \to \mu ^+\mu ^-))\) of this way of thinking about constituents are also discussed.

abstract

The influence of Bose–Einstein statistics on pion production is studied in the framework of an uncorrelated jet model. Significant positive short range correlations of like pions are found. They are in good agreement with experimentally observed correlations in the azimuthal angle. An increase of the strength of such Bose-type correlations with increasing transverse momentum is predicted. Isospin invariance is shown to produce some Bose-type correlations between unlike pions too. They should be particularly pronounced in several decay channels of \(\psi \) mesons.

abstract

A method of calculating trajectory parameters in the Oxford–Rutherford type model is presented. The poles, mixing angles and residues of the \(f\) and \(f'\) trajectories are calculated at different values of momentum transfer \(t\) in the SU(3) symmetry breaking model. The contribution of different regions of phase-space can be directly examined. The contribution of configurations with overlapping clusters builds the deviation from planar trajectories for large positive \(t\).

abstract

The validity of the hypothesis that the angular distribution of shower particles produced in hadron–nucleus interactions can be parametrized by the number of slow particles emitted from the struck nucleus is tested. Relation between the mean number of slow particles and the mass number \(A\) of the target nucleus or the corresponding average number of collisions inside the target nucleus is found.

abstract

Grand angular momentum basis is used in three meson partial wave analysis. New assumptions for Ascoli analysis are proposed. By eliminating isobar model approximation we avoid problems of nonunitarity. Ascoli analysis in this basis may be additionally used for the determination of size of the meson systems.

abstract

The magnetic moments of the vector mesons and the transition magnetic moments of the vector-pseudoscalar mesons have been computed assuming that the magnetic moment operator transforms as the (24,3) component of the SU(10)-symmetry and has been compared with the similar results obtained in SU(8). It has been found that for both charged and uncharged particles with non-vanishing hypercharge the values remain unchanged. However, for the uncharged mesons with \(Y = 0\), \(C = C'\) = 0, the results differ considerably. For example the magnetic moment of \(\psi \) particle is given by \(\mu (\psi )=(64/25)\mu (\varrho ^0)\) in this case in contrast to the result of SU(8):\(\mu (\psi )=4\mu (\varrho ^0)\).

abstract

A simple model of charge symmetry breaking nuclear forces is related directly to charge asymmetry in the low energy \(^1{\rm {\bf S}}_0\) nucleon–nucleon scattering parameters. Using this model charge asymmetry in the effective range theory parameters is related to the charge asymmetric term in the nuclear binding energies of heavy nuclei, \(E_a(N-Z)\). The role of the short-range two-body correlations induced by the dominating charge independent nucleon–nucleon potential is studied and is found to be very important when calculating \(E_a\). The value of \(E_a\) is found to be very sensitive to the charge asymmetry in the effective range while being quite insensitive to charge asymmetry in the scattering length. The use of experimental value of \(E_a\) in the study of the charge symmetry breaking component of nuclear forces is proposed.

abstract

The experimental data on the difference of strength function for two spin states of a number of nuclei is considered and comparison is made with the theoretically expected difference. The last is caused by the fluctuation of values of neutron widths and level spacings. It is shown that deviations observed in experiment have statistical character only.